wabco hydraulic pump motor failure 2 free sample

2. After the vehicle sat overnight all the brake fluid would return to the Master Cylinder reservoir (MAX line). I�m thinking this is an indicator the fluid was bypassing the seals because of debris in the fluid getting stuck under the seals or the seals were going bad?

Conclusion: I�m now a believer in changing your brake fluid every 2 years! I also think RV brake fluid gets abused when braking 20,000 plus lbs going down mountains. I recommend replacing your brake fluid with DOT 5.1, not DOT 3.DOT 5.1 has a 90* higher wet boiling point. You can mix (DOT 3, DOT 4 & DOT 5.1)�Don�t use �DOT 5�

2 Service Notes About This Manual This manual contains maintenance procedures for Meritor WABCO s Hydraulic Power Brake (HPB) system for trucks, tractors and buses. Before You Begin 1. Read and understand all instructions and procedures before you begin to service components. 2. Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. 3. Follow your company s maintenance and service, installation, and diagnostics guidelines. 4. Use special tools when required to help avoid serious personal injury and damage to components. Hazard Alert Messages and Torque Symbols Maintenance Manual 38, Hydraulic ABS for Medium-Duty Trucks, Buses and Motor Home Chassis (C Version Hydraulic ABS) Maintenance Manual 39, Hydraulic ABS for Medium-Duty Trucks, Buses and Motor Home Chassis (D Version Hydraulic ABS) Maintenance Manual MM-0677, Hydraulic Anti-Lock Braking Systems (HABS) for Medium-Duty Trucks, Buses and Motor Home Chassis (E Version Hydraulic ABS) Visit Literature on Demand on meritor.com to access and order additional information. Contact the Meritor OnTrac Customer Call Center at (United States and Canada); (Mexico); or OnTrac@meritor.com. If Tools and Supplies are Specified in This Manual Call Meritor s Commercial Vehicle Aftermarket at to obtain Meritor tools and supplies. WARNING A Warning alerts you to an instruction or procedure that you must follow exactly to avoid serious personal injury and damage to components. CAUTION A Caution alerts you to an instruction or procedure that you must follow exactly to avoid damage to This symbol alerts you to tighten fasteners to a specified torque value. How to Obtain Additional Maintenance, Service and Product Information Publications Refer to the following publications for more information on servicing Meritor WABCO s Hydraulic Power Brake (HPB) systems. Information contained in this publication was in effect at the time the publication was approved for printing and is subject to change without notice or liability. Meritor WABCO reserves the right to revise the information presented or to discontinue the production of parts described at any time. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

3 Contents pg. i Asbestos and Non-Asbestos Fibers 1 Section 1: Introduction Overview System Components 3 How the HPB System Works 5 Section 2: Wiring Diagram HPB Wiring Diagram for Multiplex Vehicles 6 HPB Connector Diagram for Multiplex Vehicles 7 HPB Wiring Diagram for Non-Multiplexed Vehicles 8 HPB Connector Diagram for Non-Multiplexed Vehicles 9 Section 3: Troubleshooting and Testing Testing the System Meritor WABCO TOOLBOX Software Connecting TOOLBOX Software 10 Hydraulic Power Brake Menus and Toolbars 14 Standard Testing Test Equipment: Volt-Ohm Meter (VOM) System Requirements and Component Tests Tire Size Range Checking Power, Ground and Load Test 15 Standard Component Testing Indicator Lamps Sensor Adjustment Vehicle Test Drive 16 Safety Features Towing Procedure for Navistar CE Buses 17 Warning Lamps 18 SPN, SID, FMI Diagnostic Trouble Code List 50 Section 4: Removal and Installation Removal Hydraulic Compact Unit 53 Installation Hydraulic Compact Unit 54 Removal HCU Reservoir 55 Installation HCU Reservoir 56 Removal HCU Accumulators 58 Installation HCU Accumulators 60 Removal Electronic Control Unit (ECU) 62 Installation Electronic Control Unit (ECU) 63 Parameter Downloading pg. 66 Removal Hydraulic Compact Unit (HCU) Relay Valve 67 Installation Hydraulic Compact Unit (HCU) Relay Valve 68 Removal Hydraulic Compact Unit (HCU) Pump 69 Installation Hydraulic Compact Unit (HCU) Pump 70 Removal Master Cylinder Replacement Information Master Cylinder 73 Installation Master Cylinder 75 Removal Master Cylinder Reservoir 77 Installation Master Cylinder Reservoir 79 Removal Master Cylinder Foot Brake Switch 80 Installation Master Cylinder Foot Brake Switch Removal Master Cylinder Fluid Level Sensor Switch Installation Master Cylinder Fluid Level Sensor 81 Removal Parking Brake Pressure Supply Valve 83 Installation Parking Brake Pressure Supply Valve 85 Removal Low Pressure Hose 86 Installation Low Pressure Hose 87 Lubrication Wheel Speed Sensor Specification 88 Removal Front Axle Wheel Speed Sensor Installation Front Axle Wheel Speed Sensor 89 Removal Rear Axle Wheel Speed Sensor Installation Rear Axle Wheel Speed Sensor 90 Section 5: Brake Bleeding Procedures 91 Brake Bleeding Procedures Pressure Bleed Procedures Master Cylinder Circuit

4 Contents pg. 92 Brake Caliper Circuit 95 Spring-Applied/Hydraulic Release Parking Brake Circuit 96 Changing Hydraulic Brake Fluid 97 Brake Fluid Replacement Requirement Filling the Hydraulic Power Brake (HPB) Master Cylinder Reservoir 99 Section 6: Appendix Leak Check Procedure for Meritor WABCO HPB System Check the HPB System for Brake Fluid Leaks System Test pg.

5 Asbestos and Non-Asbestos Fibers ASBESTOS FIBERS WARNING The following procedures for servicing brakes are recommended to reduce exposure to asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets are available from Meritor. Hazard Summary Because some brake linings contain asbestos, workers who service brakes must understand the potential hazards of asbestos and precautions for reducing risks. Exposure to airborne asbestos dust can cause serious and possibly fatal diseases, including asbestosis (a chronic lung disease) and cancer, principally lung cancer and mesothelioma (a cancer of the lining of the chest or abdominal cavities). Some studies show that the risk of lung cancer among persons who smoke and who are exposed to asbestos is much greater than the risk for non-smokers. Symptoms of these diseases may not become apparent for 15, 20 or more years after the first exposure to asbestos. Accordingly, workers must use caution to avoid creating and breathing dust when servicing brakes. Specific recommended work practices for reducing exposure to asbestos dust follow. Consult your employer for more details. Recommended Work Practices 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other operations to reduce risks to unprotected persons. OSHA has set a maximum allowable level of exposure for asbestos of 0.1 f/cc as an 8-hour time-weighted average and 1.0 f/cc averaged over a 30-minute period. Scientists disagree, however, to what extent adherence to the maximum allowable exposure levels will eliminate the risk of disease that can result from inhaling asbestos dust. OSHA requires that the following sign be posted at the entrance to areas where exposures exceed either of the maximum allowable levels: DANGER: ASBESTOS CANCER AND LUNG DISEASE HAZARD AUTHORIZED PERSONNEL ONLY RESPIRATORS AND PROTECTIVE CLOTHING ARE REQUIRED IN THIS AREA. 2. Respiratory Protection. Wear a respirator equipped with a high-efficiency (HEPA) filter approved by NIOSH or MSHA for use with asbestos at all times when servicing brakes, beginning with the removal of the wheels. 3. Procedures for Servicing Brakes. a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the HEPA vacuum to loosen and vacuum residue from the brake parts. b. As an alternative procedure, use a catch basin with water and a biodegradable, non-phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. The solution should be applied with low pressure to prevent dust from becoming airborne. Allow the solution to flow between the brake drum and the brake support or the brake rotor and caliper. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. c. If an enclosed vacuum system or brake washing equipment is not available, employers may adopt their own written procedures for servicing brakes, provided that the exposure levels associated with the employer s procedures do not exceed the levels associated with the enclosed vacuum system or brake washing equipment. Consult OSHA regulations for more details. d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for use with asbestos when grinding or machining brake linings. In addition, do such work in an area with a local exhaust ventilation system equipped with a HEPA filter. e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, flammable solvents, or solvents that can damage brake components as wetting agents. 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for use with asbestos. When you replace a HEPA filter, wet the filter with a fine mist of water and dispose of the used filter with care. 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to vacuum work clothes after they are worn. Launder them separately. Do not shake or use compressed air to remove dust from work clothes. 6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters with care, such as in sealed plastic bags. Consult applicable EPA, state and local regulations on waste disposal. Regulatory Guidance References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, are made to provide further guidance to employers and workers employed within the United States. Employers and workers employed outside of the United States should consult the regulations that apply to them for further guidance. NON-ASBESTOS FIBERS WARNING The following procedures for servicing brakes are recommended to reduce exposure to non-asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets are available from Meritor. Hazard Summary Most recently manufactured brake linings do not contain asbestos fibers. These brake linings may contain one or more of a variety of ingredients, including glass fibers, mineral wool, aramid fibers, ceramic fibers and silica that can present health risks if inhaled. Scientists disagree on the extent of the risks from exposure to these substances. Nonetheless, exposure to silica dust can cause silicosis, a non-cancerous lung disease. Silicosis gradually reduces lung capacity and efficiency and can result in serious breathing difficulty. Some scientists believe other types of non-asbestos fibers, when inhaled, can cause similar diseases of the lung. In addition, silica dust and ceramic fiber dust are known to the State of California to cause lung cancer. U.S. and international agencies have also determined that dust from mineral wool, ceramic fibers and silica are potential causes of cancer. Accordingly, workers must use caution to avoid creating and breathing dust when servicing brakes. Specific recommended work practices for reducing exposure to non-asbestos dust follow. Consult your employer for more details. Recommended Work Practices 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other operations to reduce risks to unprotected persons. 2. Respiratory Protection. OSHA has set a maximum allowable level of exposure for silica of 0.1 mg/m3 as an 8-hour time-weighted average. Some manufacturers of non-asbestos brake linings recommend that exposures to other ingredients found in non-asbestos brake linings be kept below 1.0 f/cc as an 8-hour time-weighted average. Scientists disagree, however, to what extent adherence to these maximum allowable exposure levels will eliminate the risk of disease that can result from inhaling non-asbestos dust. Therefore, wear respiratory protection at all times during brake servicing, beginning with the removal of the wheels. Wear a respirator equipped with a high-efficiency (HEPA) filter approved by NIOSH or MSHA, if the exposure levels may exceed OSHA or manufacturers recommended maximum levels. Even when exposures are expected to be within the maximum allowable levels, wearing such a respirator at all times during brake servicing will help minimize exposure. 3. Procedures for Servicing Brakes. a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the HEPA vacuum to loosen and vacuum residue from the brake parts. b. As an alternative procedure, use a catch basin with water and a biodegradable, non-phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. The solution should be applied with low pressure to prevent dust from becoming airborne. Allow the solution to flow between the brake drum and the brake support or the brake rotor and caliper. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. c. If an enclosed vacuum system or brake washing equipment is not available, carefully clean the brake parts in the open air. Wet the parts with a solution applied with a pump-spray bottle that creates a fine mist. Use a solution containing water, and, if available, a biodegradable, non-phosphate, water-based detergent. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA when grinding or machining brake linings. In addition, do such work in an area with a local exhaust ventilation system equipped with a HEPA filter. e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, flammable solvents, or solvents that can damage brake components as wetting agents. 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA, to minimize exposure. When you replace a HEPA filter, wet the filter with a fine mist of water and dispose of the used filter with care. 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to vacuum work clothes after they are worn. Launder them separately. Do not shake or use compressed air to remove dust from work clothes. 6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters with care, such as in sealed plastic bags. Consult applicable EPA, state and local regulations on waste disposal. Regulatory Guidance References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, are made to provide further guidance to employers and workers employed within the United States. Employers and workers employed outside of the United States should consult the regulations that apply to them for further guidance. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) i

6 1 Introduction 1 Introduction Overview Meritor WABCO s Hydraulic Power Brake (HPB) is a braking and vehicle control system for Business Class trucks, Classes 4 through 7, and buses that are equipped with hydraulic brakes. The HPB system provides the following functions. Full power brake performance Brake control functions including Anti-Lock Braking System (ABS), Automatic Traction Control (ATC) and Electronic Brake force Distribution (EBD) Optional parking brake control Figure 1.2 HCU WITH OPTIONAL POWER PARKING BRAKE PRESSURE SUPPLY VALVE PRESSURE SUPPLY VALVE System Components The HPB system consists of two main components the Hydraulic Compact Unit (HCU) and a dual circuit master cylinder. The HPB system is also available with an optional parking brake pressure supply valve. Figure 1.1 and Figure 1.2 illustrate the HPB system with and without the park brake supply valve. Figure 1.3 illustrates the master cylinder assembly. Figure 1.3 Figure 1.2 MASTER CYLINDER ASSEMBLY c Figure 1.1 HCU WITHOUT OPTIONAL POWER PARKING BRAKE SUPPLY VALVE a Figure 1.3 Figure b Hydraulic Compact Unit The HCU consists of an electronic control unit, two independent electric motors driving two piston pumps, two accumulators, a dual circuit fluid reservoir with integrated filters, pressure relief valves, solenoid valves and a dual circuit relay valve. The HCU is mounted to the vehicle frame rail with two brackets. Figure 1.4. WARNING Do not drive the vehicle if a HPB system failure has occurred. Loss of braking ability may occur, resulting in an accident and serious personal injury. The HCU generates the service brake pressure. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 1

7 1 Introduction Two pump motors drive the piston pumps to build hydraulic pressure. The pressure is stored in accumulators. The motors are not serviceable. The motors cannot be replaced without replacing the entire HCU. The accumulators are two gas-filled hydraulic accumulators. The accumulators store energy supplied by the pumps. Accumulators are sealed at the factory and are non-refillable. Accumulators may be replaced as a set without replacing the entire HCU. The ECU processes sensor signals and generates solenoid valve commands to reduce, maintain or increase brake pressure for control function. The ECU constantly monitors the pressure in the accumulators, using one pressure sensor per brake circuit. The ECU may be replaced without replacing the complete HCU. The optional pressure supply valve controls the Spring-Applied/ Hydraulic Released (SAHR) parking brake. The pressure supply valve is mounted on the HCU. The pressure supply valve may be replaced without replacing the entire HCU. The dual circuit HCU reservoir holds the hydraulic brake fluid. (The reservoir may be replaced without replacing the entire HCU.) The relay valve is mounted on the bottom of the HCU and may be replaced without replacing the entire HCU. Master Cylinder Assembly The dual circuit master cylinder in conjunction with a relay valve provides the translation of brake pedal force into hydraulic braking pressure, and sends the driver s demand signal to the HCU. Figure 1.5. The foot brake switch provides brake status to the ECU and eliminates the need for a brake light switch. The master cylinder reservoir holds the additional hydraulic brake fluid. The fluid sensor switch monitors fluid level in the master cylinder reservoir. The master cylinder reservoir and both master cylinder switches may be replaced without replacing the entire master cylinder. The master cylinder cap provided by Meritor WABCO contains a special gore material that allows the reservoir to breathe, and serves as a filter to help prevent contaminants from getting into the reservoir. This is the only cap approved for use with Meritor WABCO HPB. NOTE: The ability of the master cylinder cap to breathe is critical to correct brake system function. If the cap becomes contaminated, it will need to be replaced. Figure 1.4 HYDRAULIC COMPACT UNIT WITHOUT PRESSURE SUPPLY VALVE DUAL CIRCUIT HCU RESERVOIR Figure 1.5 MASTER CYLINDER RESERVOIR MASTER CYLINDER ASSEMBLY VENTED RESERVOIR CAP ECU RELAY VALVE FOOT BRAKE SWITCH PUMP MOTORS (2) FLUID LEVEL SENSOR SWITCH Figure 1.5 SECONDARY CIRCUIT (MR-REAR AXLE) PRIMARY CIRCUIT (MF-FRONT AXLE) a ACCUMULATORS b Figure Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

8 1 Introduction Wheel-End Sensors A Meritor WABCO wheel speed sensor is installed at each wheel whose speed is to be monitored. These sensors generate electronic signals which are sent to the ECU. A sensor spring clip holds the wheel speed sensor in place. Figure 1.6. The sensor and sensor clip must be lubricated before installation and whenever wheel-end maintenance is performed. Figure 1.6 Figure 1.6 TOOLBOX Software TOOLBOX Software is a PC-based diagnostics program required to diagnose HPB system faults. For HPB, version 9.0 or higher is recommended. TOOLBOX Software is available at Figure 1.7. Figure 1.7 Figure 1.7 Low Pressure Hose SENSOR SPRING CLIP WHEEL SPEED SENSOR a a The Removal and Installation section of this manual contains service information for a low pressure hose which is not produced by Meritor WABCO but is an integral part of the HPB system. Spring-Applied Hydraulic Release (SAHR) Parking Brake Canister (Optional) NOTE: The SAHR canister is not produced by Meritor WABCO and is an optional feature. Please consult the OEM for maintenance and service information. On vehicles equipped with hydraulic parking brakes, the SAHR canister controls the force applied to the parking brake cable. Internal springs are used to apply tension to the parking brake cable, which applies the parking brake. When pressurized brake fluid is routed to the SAHR canister, the hydraulic pressure overcomes the internal springs to relax the parking brake cable, which releases the parking brake. The SAHR parking brake canister is typically located inside the driver s side frame rail, forward of the rear axles. Vehicles not equipped with hydraulic parking brakes have mechanical or air (Spring Applied Air Released, SAAR) parking brakes. Please consult the OEM for maintenance and service information. WARNING Never drive the vehicle if the parking brake cable is disconnected or if the parking brake system is not operating correctly. Driving the vehicle without a correctly functioning parking brake system can result in an accident and serious personal injury. Parking Brake Switch The parking brake switch (optional) is a three-position electrical switch (apply, neutral and release). It controls the driver-requested operation of the parking brake. How the HPB System Works Meritor WABCO s hydraulic power braking system provides the energy required to actuate the brakes and control the electronic brake force distribution (EBD), ABS and ATC functions. The HCU is activated each time the ignition is turned on or whenever the driver steps on the brake pedal. If the system is equipped with the optional power park brake, the HCU also supplies the energy to release and control the service and park brakes. The Meritor WABCO HPB system for trucks is illustrated in Figure 1.8. A complete HPB system layout, with hydraulic brake lines, appears in the Appendix. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 3

9 1 Introduction Figure 1.8 HPB SYSTEM LAYOUT HCU RESERVOIR MASTER CYLINDER RESERVOIR HCU ASSEMBLY PRESSURE SUPPLY VALVE PARKING BRAKE MASTER CYLINDER ASSEMBLY ACCUMULATORS (2) RELAY VALVES ECU WHEEL-END SENSORS (4) FRONT AXLE REAR AXLE a Figure 1.8 Functional Description Hydraulic energy is stored in the gas-filled hydraulic accumulators, one for each circuit. When the vehicle s ignition is turned on, internal pumps are activated and fill both accumulators with pressurized hydraulic brake fluid. Two internal sensors, one for each accumulator, measure pressure and the ECU continuously monitors and controls pressure. During normal operation, the ECU actuates two separate power drivers for the electric motors, keeping the pressure level within the system at desired limits. Two pressure relief valves provide safety against overpressurization. When the brake pedal is applied, the master cylinder provides a hydraulic signal to the relay valve. Proportional to that signal, the accumulators release pressure to the brake calipers. When the pedal is released, brake fluid returns from the brake calipers to the reservoir, and line pressure is reduced to zero. For ABS, wheel pressure is individually modulated by eight integrated ABS solenoid valves in the ECU/HCU. For ATC, the normally closed ATC solenoid valve in the ECU is actuated and hydraulic energy is supplied to the sensed wheel. At the same time, the normally open ATC valve is actuated to prevent fluid flow back into the reservoir. The brake pressure is then modulated by the corresponding ABS solenoid valves. WARNING Do not install any add-on hydraulic devices to the HPB system. A loss of braking ability may occur, resulting in an accident and serious personal injury. 4 Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

10 2 Wiring Diagram 2 Wiring Diagram HPB Wiring Diagram for Multiplex Vehicles The Meritor WABCO HPB electronic control unit interface wiring diagram for multiplex vehicles is shown in Figure 2.1. Figure 2.1 WIRING DIAGRAM FOR MULTIPLEX (MUX) VEHICLES WITH POWER BRAKE OPTION WHEEL PRESSURE MODULATION SOLENOIDS ATC SOLENOIDS PUMP MOTOR 2 PUMP MOTOR 1 P P FRONT RIGHT REAR LEFT REAR RIGHT ATC FRONT LEFT NO IV OV IV OV IV OV IV OV NC ELECTRONIC CONTROL UNIT 31-PIN CONNECTOR 2-PIN CONNECTOR GRD STUD 1 GRD STUD 2 30A 30A 30A GRD STUD 3 SENSOR REAR RIGHT SENSOR REAR LEFT SENSOR FRONT RIGHT SENSOR FRONT LEFT V BATTERY FEED CUTOFF SOLENOID + 2x0.75 mm2 TWISTED 2x0.75 mm2 TWISTED 2x0.75 mm2 TWISTED 2x0.75 mm2 TWISTED LOW BRAKE FLUID BRAKE SWITCH CAN HIGH ACC. SAE J1939 DIAGNOSE "A" ACC. SAE J1587 PARKING BRAKE SWITCH REFERENCE GROUND IGNITION * SOLENOID VALVE GROUND * SOLENOID VALVE SUPPLY * PUMP MOTOR 2 GROUND * PUMP MOTOR 2 SUPPLY BRAKE LIGHT SIGNAL CAN LOW DIAGNOSE "B" 560R 680R 1 1 1K 2 2 3K 27K 3 * PUMP MOTOR 1 GROUND * PUMP MOTOR 1 SUPPLY 5A 5A IGNITION SWITCH PRESSURE SUPPLY VALVE 1 2 PIN 7 GROUND IGNITION 1 2 C A B TRAVEL SWITCH PARKING BRAKE a Figure 2.1 Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 5

11 2 Wiring Diagram HPB Connector Diagram for Multiplex Vehicles The Meritor WABCO HPB electronic control unit interface connector diagram for multiplex vehicles is shown in Figure 2.2. Figure 2.2 PIN IDENTIFICATION FOR WIRE HARNESS CONNECTORS TO THE ECU (9511) PRESSURE SUPPLY VALVE (OPTIONAL) CUT OFF SOLENOID (OPTIONAL) ABS OFFROAD SWITCH (OPTIONAL) MASTER CYLINDER BRAKE SWITCH IGNITION 12V BRAKE SIGNAL NOT USED REFERENCE GROUND SAHR TRAVEL SWITCH (OPTIONAL) LOW BRAKE FLUID PARKING BRAKE DASH SWITCH J HIGH J1939 LOW NOT USED NOT USED PUMP MOTOR 2 SUPPLY 12V+ SOLENOID VALVE SUPPLY 12V+ PUMP MOTOR 2 GROUND SOLENOID VALVE GROUND NOT USED NOT USED REAR RIGHT WHEEL SPEED SENSOR REAR LEFT WHEEL SPEED SENSOR FRONT LEFT WHEEL SPEED SENSOR X FRONT RIGHT WHEEL SPEED SENSOR 30 URAT1 30A 26 J1587 DIAG. B + LOW 31 J1587 DIAG. A + HIGH b Figure Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

12 2 Wiring Diagram HPB Wiring Diagram for Non-Multiplexed Vehicles The Meritor WABCO HPB electronic control unit interface wiring diagram for non-multiplexed vehicles is shown in Figure 2.3. Figure 2.3 Figure a Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 7

13 2 Wiring Diagram HPB Connector Diagram for Non-Multiplexed Vehicles The Meritor WABCO HPB electronic control unit interface connector diagram for multiplex vehicles is shown in Figure 2.4. Figure 2.4 X CAN-L 15 SAE J1939 CAN-L 14 ATC-L 13 BUZZER-RELAY 12 PARKING BRAKE SWITCH 11 BRAKE ACUATION SWITHC 10 FLUID LEVEL SWITHC 9 8 PARKING BRAKE MONITOR SWITCH 7 REF-GND 6 PB-CUTOFF 5 PB-SUPPLY 4 BLR-RELAY 3 DBR-RELAY 2 UIGN 5A 1 A-LINE 31 B-LINE SAE J GM 30 IG SENSOR FR 25 IGM 29 IG SENSOR FL 24 IGM 28 IG SENSOR RL 23 IGM 27 IG SENSOR RR 22 ABS WARNING 21 LAMP RELAY BRAKE WARNING 20 LAMP RELAY A 30A UBAT UBAT X2 30 URAT1 30A a Figure Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

14 3 Troubleshooting and Testing 3 Troubleshooting and Testing the System This section contains information for testing the HPB system with TOOLBOX Software, and for performing standard component and electrical tests. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. Exhaust gas contains poison. When testing a vehicle with the engine running, test in a well-ventilated area or route the exhaust hose outside. To avoid serious personal injury, keep away, and keep test equipment away, from all moving or hot engine parts. To avoid unwanted vehicle movement when testing, set the parking brake and place the gear selector in NEUTRAL (manual transmission), or PARK (automatic transmission) unless otherwise directed. Failure to do so may result in serious personal injury. Connecting TOOLBOX Software To connect TOOLBOX Software to the vehicle, a RP1210A compliant device will be needed. Once TOOLBOX Software is connected and open, verify the adapter settings are correct. To access Adapter Selection for TOOLBOX Software 11 or newer, click on Utilities from the main TOOLBOX page or under System Setup in J1707 TOOLBOX from the main TOOLBOX page. To access Comport Settings for TOOLBOX Software versions prior to TOOLBOX Software 11 click on System Setup from the main TOOLBOX page. Make sure the Vendor: and Adapter: drop-downs are set for the device being used and set the Protocol: drop-down to J1708, and click OK. Figure 3.1. Figure 3.1 Never drive the vehicle if the parking brake cable is disconnected or if the parking brake system is not operating correctly. Driving the vehicle without a correctly functioning parking brake system can result in an accident and serious personal injury. Refer to, and follow, the vehicle manufacturer s Warnings, Cautions and service procedures. Meritor WABCO TOOLBOX Software NOTE: The HPB system does not have blink code capability and Meritor WABCO TOOLBOX Software is needed to communicate with the system. Use TOOLBOX Software to obtain DTCs and verify the activation of various system components. Turn valves, pump and retarder relay (if available) on and off (Valve Activation Menu) Turn indicator lamps on and off (Miscellaneous Output Activation Menu) NOTE: To obtain TOOLBOX Software, go to Figure 3.1 NOTE: When switching between J1939 and J1708 communications, vehicle ignition must be cycled between sessions to correctly communicate with ECU. NOTE: TOOLBOX Software must be connected to the vehicle and the vehicle ignition must be ON in order to display information. If unable to communicate with the ECU: Verify device and data link connections are secure a Verify the device is RP1210A compliant and that the comport settings (Vendor, Protocol, Adapter) in TOOLBOX Software are correct. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 9

15 3 Troubleshooting and Testing Verify the device software and firmware is up to date. Figure 3.3 Check all the powers and grounds coming to the ECU including load testing. Check J1587 circuit at the ECU and the data link connector. Hydraulic Power Brake Menus and Toolbars Select Hydraulic ABS from the TOOLBOX Software Main Menu. TOOLBOX Software senses the type of ECU being used and displays the HPB Main Screen. Main HPB Screen This screen provides icons and pull-down menu task selections. It also provides information about the current status of Meritor WABCO HPB. Figure 3.2. Figure 3.2 Figure 3.3 Faults a WARNING Do not drive the vehicle if active faults are present. Driving the vehicle with active faults present can result in an accident and serious personal injury. Select Faults to display the Fault Information screen. Figure 3.4. NOTE: The Fault Information screen is also accessible from the HPB Main Menu. Figure a Figure 3.2 ECU information is read once from the ECU and does not change. All other information (e.g., wheel sensors, voltages and fault information) is read and updated continuously. Display Select Display from the HPB Main Screen. A pull-down menu will appear. Figure 3.3. Figure a The Fault Information screen contains a description of each fault, including the type of fault (Active or Stored), SID and FMI number. Repair instructions for the fault appear at the bottom of the screen. 10 Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

16 3 Troubleshooting and Testing Faults that occur after the screen is displayed will not appear until a screen update is requested. Use the Update button at the bottom of the screen to refresh the fault information table and display a new list of faults. Figure 3.6 After making any required repairs, use the Clear Faults button to clear the fault. Clear each fault as it is repaired. The Update button should be used after all faults are repaired. Cycle the ignition after clearing the faults. NOTE: When all faults are cleared, you need to drive the vehicle above 5 mph before the ABS light will go out. Use the Save or Print button to save or print the fault information data. Select Exit to close this section. Wheel Speed Select Wheel Speed to display the Wheel Speed screen. Figure 3.5. Figure 3.5 Figure a The Counters screen provides an overview of HPB component performance (pump hours, brake events, etc.) as well as general vehicle activity such as ignition cycles. Occurrences displayed on this screen accumulate until the Clear button is selected. Component Tests Select Component Tests from the HPB Main Screen. A pull-down menu will appear. Figure 3.7. Figure a Figure 3.5 Use the Wheel Speed screen to verify that sensors are connected at each wheel. Speed at a sensed wheel (FL, FR, RL, RR) indicates sensors are installed, but does not verify correct sensor installation. Wheel speed sensor installation information is available in the Removal and Installation section. Counters Select Counters to display the Counters screen. Figure 3.6. Figure a Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 11

17 3 Troubleshooting and Testing Valves Select Valves to display the Valve Activation test screen. Figure 3.8. Figure 3.9 Figure a Figure 3.9 As each lamp is tested, check the actual lamp to verify correct operation. Select Close to exit this screen. Parking Brake WARNING Park the vehicle on a level surface. Block the front and rear wheels to prevent vehicle movement. Failure to do so can result in unwanted vehicle movement causing serious personal injury. Select Parking Brake to display the Parking Brake test screen. Figure a Figure 3.10 Figure 3.8 The Valve Activation test screen lets you activate the HPB valves to check for correct activation and to verify correct brake line installation. Click on the valve you wish to test, then click the Send button to actuate the component. Component activation status appears in the Status box field. Select Close to exit this screen. Lamps Select Lamps to display the Lamp Test screen. Figure a Figure Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

18 3 Troubleshooting and Testing Select Release or Apply, then select Send to test the parking brake. Select Close to exit this screen. Figure 3.12 Relay (Only on Non-Multiplex Vehicles) Select Relay to display the Activate Relay test screen. Figure Figure a Figure 3.12 Figure a This screen allows you to send a limit engine torque command to the engine or a disable retarder command to the retarder. Select the data link destination (engine or retarder), then select Send to test. Use the Stop button to end testing. Select Close to exit this screen. The vehicle must be running with the engine RPM increased ( RPM) in order for this function to work. Disable ATC Select Disable ATC to send a command to the ECU to disable automatic traction control. ATC will remain disabled until the enable command is sent, or until the vehicle ignition is cycled. ATC must be disabled for dynamometer testing. Enable ATC Select Enable ATC to send a command to the ECU to enable automatic traction control. This is the normal state of the ECU. Figure 3.7. This screen allows you to turn the retarder relay on or off. This is helpful in verifying correct operation, installation and wiring of the unit under test. Select Close to exit this screen. Engine Data Link Select Engine Data Link to display the Data Link test screen. Figure NOTE: The status bar on the HPB Main Menu reflects the current ATC status (enabled, disabled or not available). Miscellaneous Outputs Select Miscellaneous Outputs to display the Activate Miscellaneous Outputs test screen. Figure NOTE: Use TOOLBOX Software to test the following components: Retarder Relay (if available), Brake Light Relay (if available), Supply Valve, Cut-Off Valve, ABS Lamp, Traction Lamp, Brake Warning, Pump Front, Pump Rear, Buzzer. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 13

19 3 Troubleshooting and Testing Figure 3.13 Standard Testing Figure a Test Equipment: Volt-Ohm Meter (VOM) Use of a VOM with automatic polarity sensing is recommended. This eliminates the concern of the polarity of the meter leads during voltage measurements. System Requirements and Component Tests Tire Size Range WARNING For correct hydraulic ABS operation, front and rear tire sizes must be within 16% of each other. Do not use a tire size range that exceeds 16%. Failure to do so may cause reduced braking force and result in serious personal injury. This screen provides a check of several HPB components, as well as a way to check either inlet or outlet activity of the valves, pump or retarder relay. Highlight the component you wish to test, then select the Send button to actuate the component. Component activation status appears in the Status Box field. Select Close to exit this screen. Reset Memorized Select Reset Memorized to display the Learned Component screen. Figure Figure 3.14 Figure a Relay is an automatic default and cannot be de-selected. It indicates the ECU has memorized the installed retarder relay. Once the ECU has seen a retarder, it expects to see it every time the vehicle is powered up. Calculate the tire size with the following equation: % Difference = { RPM = tire revolutions per mile RPM Steer 1} x 100 RPM Drive Checking Power, Ground and Load Test CAUTION When troubleshooting or testing the ABS, be careful not to damage the connector terminals. If connector terminals are damaged, they must be replaced. There are 2 connectors at the HPB ECU, a 2-pin connector and a 31-pin connector. When checking power and ground for any of the ECU circuits, it is recommended to check all the power and ground circuits as there are redundant powers and grounds. Disconnect the 2-pin and 31-pin connectors and verify all the lock tabs are there and good, check for any signs of damage, moisture or corrosion. 14 Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

20 3 Troubleshooting and Testing Ground Checks Check all the ground wire circuits, with the key off, disconnect the 2-pin and 31-pin connectors and in the 2-pin harness connector check resistance to ground pin 1 and in the 31-pin harness connector check resistance to ground pins 6, 18, 19. All readings should be less than 1 ohm, if the readings are not in spec, may need to review wiring diagnostics and repair with the OEM. Voltage Checks Check all the power wire circuits, with the key off, disconnect the 2-pin and 31-pin connectors. In the 2-pin harness connector, check voltage to ground pin 2 and in the 31-pin harness connector, check voltage to ground pins 1, 16, 17. All readings should be approximately 12 volts, except pin 17. There should be no voltage key off. With the key on, recheck voltage at pin 2 of the 2-pin connector and pins 1, 16, 17 of the 31-pin connector. All readings should be approximately 12 volts. If the readings are not in spec, may need to review wiring diagnostics and repair with the OEM. Load Test A compromised wire or circuit may still be able to provide resistance and voltage readings that would be within specification for a Digital Volt Ohm Meter or test light, but might not be capable of handling enough current to allow the system to function correctly. To make sure of the integrity of the wire or circuit, a load test is necessary. With the key on load, test across pins 1-2 of the 2-pin harness connector and pins 1-6, 16-18, of the 31-pin harness connector with a device that will draw about 5 amps (such as a Sealed Beam headlight) for approximately 10 seconds. The headlamp should be bright, if the lamp does not light, is dim or flickers, it would indicate an issue with the wiring, may need to review wiring diagnostics and repair with the OEM. Standard Component Testing Indicator Lamps If the indicator lamps do not come on after the ignition is turned on, or it comes on but does not go out after three seconds, check all ABS fuses or circuit breakers and replace if necessary. After checking the indicator lamps, make repairs as necessary. Sensor Adjustment On steering axles, the sensor is typically accessible on the in-board side of the steering knuckle. On drive axles, the sensor is typically accessible on the in-board side of the rear axle spindle. To adjust the sensor, push the sensor in until it contacts the tooth wheel. Do not pry or push sensors with sharp objects. Sensors will self-adjust during wheel rotation. NOTE: No gap is allowed at installation. During normal operation, the gap should not be greater than 0.04-inch (1.02 mm). Vehicle Test Drive After replacing an HPB component, use TOOLBOX Software to ensure there are not active faults, then test drive the vehicle as follows: 1. Turn ignition ON. NOTE: Depending on the vehicle, the ATC lamp may be labeled differently and some vehicles may not have an ATC lamp. Refer to the vehicle specification sheet for label designation. 2. Check the vehicle dash lamps: Most of the dash lamps for HPB come on briefly (approximately three seconds) for a bulb check, then go off. This indicates the system is O.K. If the ABS and ATC lamps do not go off within 3 seconds after turning the ignition ON, the system is looking for a wheel speed test. Drive the vehicle at speeds of 5-10 mph (8-16 km/h). The ABS and ATC lamps will then go off if the system is O.K. If the ABS and ATC lamps do not go off after the vehicle reaches a speed of 5-10 mph (8-16 km/h), this indicates there is a system fault. Perform vehicle diagnostics and make all of the necessary repairs, including appropriate bleed procedures, before returning the vehicle to service. WARNING Do not drive the vehicle if active faults are present. Driving the vehicle with active faults present can result in an accident and serious personal injury. 3. Drive the vehicle for a short distance. Make gentle brake applications to verify brake performance. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 15

21 3 Troubleshooting and Testing Safety Features Limp Mode The HPB system has a feature known as Limp Mode In the event that power is lost at the 31-pin ECU connector or the 31-pin connector has become dislodged, power for emergency foundation braking can still be provided through the 2 pin ECU connector. Dynamic Park Brake Application, If Equipped with the Hydraulic Park Brake System In the event that the HPB system should lose all power and pressure, the park brake will automatically apply, while moving or at rest. Interlocks, If Equipped with the Hydraulic Park Brake System The HPB system with the hydraulic park brake feature may not allow the park brake to be release unless certain interlock messages are received, such as a door being left open or a wheel chair lift that is not seated correctly in the stored position. Review interlock operation and diagnostics with the OEM. Towing Procedure for Navistar CE Buses Towing Preparation: Hydraulic Powered Parking Brakes If battery power is available: 1. Place the transmission in N Neutral and turn the ignition switch to the ON position. 2. While depressing the brake pedal, push and hold the Parking Brake knob to release the parking brake. If battery power has been lost, the Parking Brake cable will have to be disconnected by following the steps below. If battery power has been lost: Use the following procedure to disconnect the Parking Brake cable. 3. While using the 15 mm wrench to hold the canister shaft, unscrew the threaded rod using an 8 mm wrench. The rod must be unscrewed approximately 2.5 inches before the cable disconnects. The cable will exhibit some resistance while being unscrewed because it is under tension. Towing Vehicle with Front Wheels Suspended When it is necessary to tow a vehicle with the front wheels suspended, extra precautions must be taken to avoid transmission or differential damage. Disconnect the axle shafts at the rear axle to prevent the wheels from driving the differential and the transmission. If axle shaft is not disconnected, remove the rear axle shafts from the axle assembly. Cover the wheel hub ends to prevent loss of axle lubricant and entrance of contaminants. Towing Vehicles with Rear Wheels Suspended Whenever possible, it is preferable to tow a disabled vehicle from the rear by raising the rear of the chassis. When towing a vehicle with the rear of the chassis suspended, the front wheels must be locked in the straight ahead position. CAUTION While removing the parking brake cable, only the threaded rod should rotate. If the cable is to be reused, do not allow the cable to twist during removal. 1. Block the wheels, place the transmission in N Neutral, and turn the ignition switch to the OFF position. 2. While using a 15 mm wrench to hold the SAHR canister shaft, loosen the jam nut on the threaded rod with a 16 mm wrench. 16 Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15)

22 3 Troubleshooting and Testing Warning Lamps Indicator Lamp Lamp Status System Condition Being Indicated Recommendation BRAKE/BRAKE PRESSURE Note: Indicator differs by model year STEADY ON and buzzer on FLASHING or STEADY ON* and buzzer on (*depending on model) Half brake system failure. One of the two brake circuits is not generating pressure or is not generating pressure at the proper rate. Braking force from the Hydraulic Power Brake may be reduced or impaired. Use Parking Brake if necessary. Full brake system failure. Both brake circuits are not generating pressure or are not generating pressure at the proper rate. Braking force from the Hydraulic Power Brake may be reduced or impaired. Use Parking Brake if necessary. OFF System pressures are in normal operating range. BRAKE FLUID STEADY ON Low brake fluid level in the Master Cylinder Reservoir. Braking force from the Hydraulic Power Brake may be reduced or impaired. Use parking brake if necessary. OFF Brake fluid level detected in the Master Cylinder is at or above MIN mark. Immediately find a location to safely park the vehicle. When safely off the road and stopped, turn off ignition and ensure the vehicle transmission is in the park position. Apply Parking Brake. Do not drive until the failure has been repaired. Immediately find a location to safely park the vehicle. When safely off the road and stopped, turn off ignition and ensure the vehicle transmission is in the park position. Apply Parking Brake. Do not drive until the failure has been repaired. Immediately find a location to safely park the vehicle. When safely off the road and stopped, turn off ignition and ensure the vehicle transmission is in the park position. Apply Parking Brake. Do not drive until the failure has been repaired. ABS STEADY ON An ABS related fault has been detected by the Have vehicle repaired as soon as possible. ECU. The advantages provided by ABS may not be fully available OFF No ABS related faults detected. TRAC CTRL STEADY ON A Traction Control related fault has been detected OR- A Traction Control event is occurring due to spinning wheels and the system is operating correctly. FLASHING Mud and Snow mode was selected using the traction control switch (switch indicator lit) OFF ATC is operating correctly, the Mud and Snow mode has not been selected and the vehicle is not experiencing an ATC event. PARK BRAKE STEADY ON Park Brake is applied. OFF Park Brake is not applied. SERVICE PARK BRAKE FLASHING/ STEADY ON A Park Brake related fault has been detected by the ECU. Braking force from Park Brake may be reduced or impaired. If the lamp remains on for over 10 seconds, there is a high likelihood of a fault in the traction control system. Have vehicle repaired as soon as possible. Immediately find a location to safely park the vehicle. When safely off the road and stopped, turn off ignition and ensure the vehicle transmission is in the park position. Apply Parking Brake. Do not drive until the failure has been repaired. OFF No Park Brake related faults detected. NOTE: If the ABS and/or ATC lamps are flashing after the parameters have been downloaded, verify the System Check Status has been set. See System Check Status in Parameter Downloading section of this manual. Meritor WABCO Maintenance Manual MM-0401 (Revised 07-15) 17

An anti-lock braking system (ABS) is a safety anti-skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses.wheels from locking up during braking, thereby maintaining tractive contact with the road surface and allowing the driver to maintain more control over the vehicle.

In 1920 the French automobile and aircraft pioneer Gabriel Voisin experimented with systems that modulated the hydraulic braking pressure on his aircraft brakes to reduce the risk of tire slippage, as threshold braking on aircraft is nearly impossible. These systems used a flywheel and valve attached to a hydraulic line that feeds the brake cylinders. The flywheel is attached to a drum that runs at the same speed as the wheel. In normal braking, the drum and flywheel should spin at the same speed. However, when a wheel slows down, then the drum would do the same, leaving the flywheel spinning at a faster rate. This causes the valve to open, allowing a small amount of brake fluid to bypass the master cylinder into a local reservoir, lowering the pressure on the cylinder and releasing the brakes. The use of the drum and flywheel meant the valve only opened when the wheel was turning. In testing, a 30% improvement in braking performance was noted, because the pilots immediately applied full brakes instead of slowly increasing pressure in order to find the skid point. An additional benefit was the elimination of burned or burst tires.

The first proper recognition of the ABS system came later with the German engineer Karl Wässel, whose system for modulating braking power was officially patented in 1928. Wässel, however, never developed a working product and neither did Robert Bosch who produced a similar patent eight years later.

By the early 1950s, the Dunlop Maxaret anti-skid system was in widespread aviation use in the UK, with aircraft such as the Avro Vulcan and Handley Page Victor, Vickers Viscount, Vickers Valiant, English Electric Lightning, de Havilland Comet 2c, de Havilland Sea Vixen, and later aircraft, such as the Vickers VC10, Hawker Siddeley Trident, Hawker Siddeley 125, Hawker Siddeley HS 748 and derived British Aerospace ATP, and BAC One-Eleven, and the Dutch Fokker F27 Friendship (which unusually had a Dunlop high pressure (200 Bar) pneumatic system in lieu of hydraulics for braking, nose wheel steering and landing gear retraction), being fitted with Maxaret as standard.

Chrysler, together with the Bendix Corporation, introduced a computerized, three-channel, four-sensor all-wheelImperial.Lincoln Continental Mark III and Ford Thunderbird, as an option;General Motors introduced the "Trackmaster" rear-wheel onlyrear-wheel drive Cadillac modelsOldsmobile Toronado.Nissan offered an EAL (Electro Anti-lock System) developed by Japanese company Denso as an option on the Nissan President, which became Japan"s first electronic ABS.

1971: Imperial Archived 2020-02-04 at the Wayback Machine became the first production car with a 4 wheel computer-operated anti-lock braking system. Toyota introduced electronically controlled anti-skid brakes on Toyota Crown.Triumph 2500 Estates were fitted with Mullard electronic systems as standard.

1976: WABCO began the development of the anti-locking braking system on commercial vehicles to prevent locking on slippery roads, followed in 1986 by the electronic braking system (EBS) for heavy-duty vehicles.

1982: Honda introduced electronically controlled multi-channel ALB (Anti Locking Brakes) as an option for the second generation of Prelude, launched worldwide in 1982. Additional info: the general agent for Honda in Norway required all Preludes for the Norwegian market to have the ALB-system as a standard feature, making Honda Prelude be the first car delivered in Europe with ABS as a standard feature. The Norwegian general agent also included a sunroof and other options to be standard equipment in Norway, adding more luxury to the Honda brand. However, the Norwegian tax system made the well-equipped car very expensive, and the sales suffered from high costs. From 1984 the ALB-system, as well as the other optional features from Honda, was no longer a standard feature in Norway.

In 1985 the Ford Scorpio was introduced to the European market with a Teves electronic system throughout the range as standard. For this the model was awarded the coveted European Car of the Year Award in 1986, with very favorable praise from motoring journalists. After this success, Ford began research into Anti-Lock systems for the rest of their range, which encouraged other manufacturers to follow suit.

In 1988, BMW introduced the first motorcycle with an electro-hydraulic ABS: the BMW K100. Yamaha Introduced the FJ1200 model with optional ABS in 1991. Honda followed suit in 1992 with the launch of its first motorcycle ABS on the ST1100 Pan European. In 2007, Suzuki launched its GSF1200SA (Bandit) with an ABS. In 2005, Harley-Davidson began offering an ABS option on police bikes.

Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects the wheel rotating significantly slower than the speed of the vehicle, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second.

The pump in the ABS is used to restore the pressure to the hydraulic brakes after the valves have released it. A signal from the controller will release the valve at the detection of wheel slip. After a valve releases the pressure supplied from the user, the pump is used to restore the desired amount of pressure to the braking system. The controller will modulate the pump"s status in order to provide the desired amount of pressure and reduce slipping.

This replaces the need to manually pump the brakes while driving on a slippery or a low traction surface, allowing to steer even in most emergency braking conditions.

A June 1999 National Highway Traffic Safety Administration (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 27.2 percent.

"ABS works with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety."

The Insurance Institute for Highway Safety released a study in 2010 that found motorcycles with ABS 37% less likely to be involved in a fatal crash than models without ABS.

A toothed-wheel ABS sensor. These are the front brake discs on a BMW R1150GS. The toothed ABS ring indicates that this bike was manufactured before November 2002.

On a motorcycle, an anti-lock brake system prevents the wheels of a powered two wheeler from locking during braking situations. Based on information from wheel speed sensors the ABS unit adjusts the pressure of the brake fluid in order to keep traction during deceleration to avoid accidents. Motorcycle ABS helps the rider to maintain stability during braking and to decrease the stopping distance. It provides traction even on low friction surfaces. While older ABS models are derived from cars, recent ABS is the result of research, oriented on the specifics of motorcycles in case of size, weight, and functionality. National and international organizations evaluate Motorcycle ABS as an important factor to increase safety and reduce motorcycle accident numbers. The European Commission passed legislation in 2012 that made the fitment with ABS for all new motorcycles above 125cc to be mandatory from 1 January 2016. Consumer Reports said in 2016 that "ABS is commonly offered on large, expensive models, but it has been spreading to several entry-level sportbikes and midsized bikes".

In 1988, BMW introduced an electronic/hydraulic ABS for motorcycles, ten years after Daimler Benz and Bosch released the first four-wheel vehicle ABS for series production. Motorcycles of BMW K100 series were optionally equipped with the ABS, which added 11 kg to the bike. It was developed together with FAG Kugelfischer and regulated the pressure in the braking circuits via a plunger piston.Honda ST1100 and the Yamaha FJ1200.

Wheel speed sensors mounted on the front and rear wheel constantly measures the rotational speed of each wheel and delivers this information to an Electronic Control Unit (ECU). The ECU detects two things: 1) if the deceleration of one wheel exceeds a fixed threshold and 2) whether the brake slip, calculated based on information of both wheels, rises above a certain percentage and enters an unstable zone. These are indicators for a high possibility of a locking wheel. To countermeasure these irregularities the ECU signals the hydraulic unit to hold or to release pressure. After signals show the return to the stable zone, the pressure is increased again. Past models used a piston for the control of the fluid pressure. Most recent models regulate the pressure by rapidly opening and closing solenoid valves.

While the basic principle and architecture has been carried over from passenger car ABS, typical motorcycle characteristics have to be considered during the development and application processes.

Piston Systems: The pressure release in this system is realized through the movement of a spring-tensioned piston. When pressure should be released, a linear motor pulls back the plunger piston and opens up more space for the fluid. The system was used for example in the ABS I (1988) and ABS II (1993) of BMW. The ABS II differed in size and an electronically controlled friction clutch was mounted on the shaft instead of a plunger. Further displacement sensors record the travel distance of the piston to allow the control unit a more precise regulation. Honda also uses this system of pressure modulation for big sports and touring bikes.

Valve and Pump Systems: The main parts which are part of the pressure modulation system are solenoid inlet and outlet valves, a pump, motor, and accumulators/reservoirs. The number of the valves differs from model to model due to additional functionalities and the number of brake channels. Based on the input of the ECU, coils operate the inlet and outlet valves. During pressure release, the brake fluid is stored in accumulators. In this open system approach, the fluid is then brought back in the brake circuit via a pump operated by a motor that is felt through pulsation on the brake lever.

Different from cars or trains, motorcycle rear and front wheels are controlled separately. If the rider only brakes with one wheel, this braked wheel tends to lock up faster than if both brakes had been applied. A Combined Braking System therefore distributes the brake force also to the non-braked wheel to lower the possibility of a lock-up, increase deceleration and reduce suspension pitch.

With a single [rear] CBS the brake pressure applied on the rear brake (pedal) is simultaneously distributed to the front wheel. A delay valve cuts the hydraulic pressure to assure that only when strong braking is applied, the pressure is also created at the front wheel. Honda"s first street motorcycle with a combined braking system (then called Unified Braking) was the 1983 GL1100. This system was derived from the 1970s RCB1000 world endurance race bike.

CBS helps to reduce the danger of wheel locks and fall downs but in certain situations, it is possible that CBS causes a fall down. If brake pressure is distributed from the rear wheel to the front wheel and the friction of the surfaces changes suddenly (puddle, ice on the street) the front wheel might lock even if only the rear brake has been applied. This would lead to a loss of stability and a fall down. CBS is therefore combined with ABS to avoid this on a motorcycle.

In 2009, Honda introduced the electronic controlled combined ABS for its high-performance sports bikes which utilize brake by wire technology. The brake input of the rider is measured by pressure sensors and the information is provided to an ECU. Together with the information of the wheel speed sensors, the ECU calculates the optimal distribution of pressure to prevent lockups and to provide the best possible deceleration. Based on this output a motor for each wheel operates a pump that builds up and regulates the brake pressure on the wheel. This system offers a fast reaction time because of the brake by wire functionality.

The MIB (Motorcycle integral Braking system) from Continental Teves and the eCBS (electronic CBS) in the enhanced Motorcycle ABS from Bosch are results of another approach. These systems are based on the pump and valve approach. Through additional valves, stronger pumps and a more powerful motor the system can actively build up pressure. The input pressure of the rider is measured with pressure sensors at the lever and pedal. The pump then builds up additional pressure adjusted to riding conditions. A partial integral System is designed for working in one direction only: front→rear or rear→front. A fully-integrated system works in both directions.

Because these systems are electronically controlled and are able to build up pressure actively, they offer the opportunity to adjust the motorcycle braking behavior to the rider. CBS and ABS can be switched off by experienced riders and also different regulation modes with higher and lower thresholds can be chosen, such as the rain or slick mode in the BMW S1000RR.

The Insurance Institute for Highway Safety (IIHS) conducted a study on the effectiveness of ABS for motorcycles and came to the conclusion that motorcycles above 250 cm3 without ABS are 37 percent more likely to be involved in fatal crashes and a study of the Swedish Road Administration came to the conclusion that 48 percent of all severe and fatal motorcycle accidents above 125 cm3 could be avoided due to motorcycle ABS.

These studies caused the EU commission to initiate a legislative process in 2010 that was passed in 2012 and led to ABS for motorcycles above 125 cm3 becoming mandatory from 2016 onwards. Organizations like the Fédération Internationale de l"Automobile and the Institute of advanced Motorists (IAM) demanded the implementation of this legislation already for 2015.United Nations (UN) started the Decade of Action for Road