wabco hydraulic pump motor failure 2 price
After doing all the recalls/things they recommend, this is the most common reoccuring failure on the system and it occurs on buses built prior to Fall of 2006. If your bus is built before October (I think) of 2006, it has seal rings on the pumps which are made out of a material that can stick in the bore in the HCU if the bus is shut down and the piston is in the depressed position. Further, this happens after the bus sits for a while (like in the summer). If the failure is in the front pump, the bus will not move since the front pump is the one that supplies the pressure to the SAHR. If the rear pump sticks, you can release the brake with a laptop and Wabco Toolbox software and drive it to the dealer. Now, the good news! Wabco has extended the warranty on these pumps (and the HCU) that were built before fall of 2006 to FIVE years! And, if you have a failure of one pump, they will replace BOTH under warranty (sometimes you have to get on the phone to Wabco yourself and wake up the call center dude though!). You didn"t mention the year or the exact conditions of the failure but this is the most common we have seen.
The other failure we see is harder to diagnose which is a bad motor in the HCU (only serviced as an assembly). Wabco has extended the warranty on the HCU as well on the above mentioned dates, but getting them to go for the HCU requires pulling teeth sometimes. They changed the way they constructed the motors after that date and to date, we have experienced no problems with the later models. The last one 2005 model I had replaced under warranty, I wound up paying ALOT to freight one in from Texas as there were none close by.
The best way to tell a pump failure is a "low pressure gradient" code and a "Pump monitor voltage low" code is usually an HCU if the rest of the electrical system is sound. Also watch out that the call center doesn"t try to get the dealer to bleed the system to get a stuck pump working. If the piston is causing the problem and they get it to work again (get the pump unstuck) it WILL break down again...usually on a Monday morning along with three other breakdowns! Just explain to the call center rep that the system hasn"t been opened up and thus....bleeding is not the problem...and the bus is in the problem date range for the pumps. There are no parts problems with getting the pumps (I have some). If the HCU is what they can"t find, good luck! Hope this helps. Let us know.
Whether it’s for cars, buses, trucks, or trailers, WABCO® is at the frontline at developing and providing products and systems to make vehicles safer and easier to control. Founded in 1869, WABCO is a major supplier of braking, stability, suspension and transmissions in the Americas and beyond. The company is recognized as introducing the modern air brake system in 1869, and continues to lead the industry in air brake design and production for the heavy duty and commercial vehicle sectors. Today, WABCO operates as a division of the German auto parts maker ZF and employs 16,000 employees in facilities in 36 countries worldwide.
About This Manual ArvinMeritor’s Customer Service CenterThis manual contains maintenance procedures for Meritor WABCO’s Call ArvinMeritor’s Customer Service Center at 800-535-5560.Hydraulic Power Brake (HPB) system for trucks, tractors and buses. Technical Electronic Library on CDBefore You Begin The DriveTrain Plus™ by ArvinMeritor Technical Electronic Library on CD contains product and service information for most Meritor1. Read and understand all instructions and procedures before you begin to service components. and Meritor WABCO products. $20. Specify TP-9853.
2. Read and observe all Warning and Caution hazard alert How to Obtain Tools and Supplies Specified messages in this publication. They provide information that can in This Manual help prevent serious personal injury, damage to components, or both. Call ArvinMeritor’s Commercial Vehicle Aftermarket at 888-725-9355 to obtain Meritor tools and supplies.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.
How to Obtain Additional Maintenance andService InformationOn the WebVisit the DriveTrain Plus™ by ArvinMeritor Tech Library atmeritorwabco.com to easily access product and service information.The Library also offers an interactive and printable Literature OrderForm.
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 (Issued 12-04) Contents
pg. i Asbestos and Non-Asbestos Fibers pg. 38 Removal Parking Brake Pressure Supply Valve 1 Section 1: Introduction 40 Installation Overview Parking Brake Pressure Supply Valve System Components 42 Removal 3 How the HPB System Works Low Pressure Hose 5 Section 2: Wiring Diagram 43 Installation HPB for Multiplex Vehicles Low Pressure Hose 6 Section 3: Troubleshooting and Testing 44 Lubrication Testing the System Wheel Speed Sensor Specification Meritor WABCO TOOLBOXTM Software Removal Hydraulic Power Brake Menus and Toolbars Front Axle Wheel Speed Sensor 10 Standard Testing 45 Installation Test Equipment: Volt-Ohm Meter (VOM) Front Axle Wheel Speed Sensor System Requirements and Component Tests Removal Tire Size Range Rear Axle Wheel Speed Sensor 11 Voltage Check Installation Standard Component Testing Rear Axle Wheel Speed Sensor Indicator Lamps 46 Removal Sensor Adjustment Master Cylinder Foot Brake Switch Vehicle Test Drive Installation Master Cylinder Foot Brake Switch 12 Section 4: Removal and Installation Removal Removal Master Cylinder Fluid Level Sensor Switch Hydraulic Compact Unit 47 Installation 15 Installation Master Cylinder Fluid Level Sensor Switch Hydraulic Compact Unit 17 Removal 48 Section 5: Brake Bleeding Procedures HCU Reservoir Brake Bleeding Procedures 20 Installation 49 Pressure Fill and Bleed HCU Reservoir Master Cylinder Circuit 23 Removal Brake Caliper Circuit HCU Accumulators 50 Spring-Applied/Hydraulic Release Parking Brake Circuit 25 Installation Changing Hydraulic Brake Fluid HCU Accumulators 52 Section 6: Appendix 27 Removal HPB System Electronic Control Unit (ECU) 28 Installation Electronic Control Unit (ECU) 29 Removal Master Cylinder Replacement Information Master Cylinder 32 Installation Master Cylinder 34 Removal Master Cylinder Reservoir 36 Installation Master Cylinder Reservoir Asbestos and Non-Asbestos Fibers
ASBESTOS FIBERS WARNING NON-ASBESTOS FIBERS WARNING The following procedures for servicing brakes are recommended to reduce exposure to 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 non-asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data available from ArvinMeritor. Sheets are available from ArvinMeritor. Hazard Summary Hazard Summary Because some brake linings contain asbestos, workers who service brakes must understand the Most recently manufactured brake linings do not contain asbestos fibers. These brake linings may potential hazards of asbestos and precautions for reducing risks. Exposure to airborne asbestos contain one or more of a variety of ingredients, including glass fibers, mineral wool, aramid fibers, dust can cause serious and possibly fatal diseases, including asbestosis (a chronic lung disease) ceramic fibers and silica that can present health risks if inhaled. Scientists disagree on the extent and cancer, principally lung cancer and mesothelioma (a cancer of the lining of the chest or of the risks from exposure to these substances. Nonetheless, exposure to silica dust can cause abdominal cavities). Some studies show that the risk of lung cancer among persons who smoke silicosis, a non-cancerous lung disease. Silicosis gradually reduces lung capacity and efficiency and who are exposed to asbestos is much greater than the risk for non-smokers. Symptoms of and can result in serious breathing difficulty. Some scientists believe other types of non-asbestos these diseases may not become apparent for 15, 20 or more years after the first exposure to fibers, when inhaled, can cause similar diseases of the lung. In addition, silica dust and ceramic asbestos. fiber dust are known to the State of California to cause lung cancer. U.S. and international Accordingly, workers must use caution to avoid creating and breathing dust when servicing agencies have also determined that dust from mineral wool, ceramic fibers and silica are potential brakes. Specific recommended work practices for reducing exposure to asbestos dust follow. causes of cancer. Consult your employer for more details. Accordingly, workers must use caution to avoid creating and breathing dust when servicing brakes. Specific recommended work practices for reducing exposure to Recommended Work Practices non-asbestos dust follow. Consult your employer for more details. 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other Recommended Work Practices 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 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other a 30-minute period. Scientists disagree, however, to what extent adherence to the maximum operations to reduce risks to unprotected persons. allowable exposure levels will eliminate the risk of disease that can result from inhaling asbestos 2. Respiratory Protection. OSHA has set a maximum allowable level of exposure for silica of 0.1 dust. OSHA requires that the following sign be posted at the entrance to areas where exposures mg/m3 as an 8-hour time-weighted average. Some manufacturers of non-asbestos brake linings exceed either of the maximum allowable levels: recommend that exposures to other ingredients found in non-asbestos brake linings be kept DANGER: ASBESTOS below 1.0 f/cc as an 8-hour time-weighted average. Scientists disagree, however, to what extent CANCER AND LUNG DISEASE HAZARD adherence to these maximum allowable exposure levels will eliminate the risk of disease that can AUTHORIZED PERSONNEL ONLY result from inhaling non-asbestos dust. RESPIRATORS AND PROTECTIVE CLOTHING Therefore, wear respiratory protection at all times during brake servicing, beginning with the ARE REQUIRED IN THIS AREA. removal of the wheels. Wear a respirator equipped with a high-efficiency (HEPA) filter 2. Respiratory Protection. Wear a respirator equipped with a high-efficiency (HEPA) filter approved by NIOSH or MSHA, if the exposure levels may exceed OSHA or manufacturers’ approved by NIOSH or MSHA for use with asbestos at all times when servicing brakes, beginning recommended maximum levels. Even when exposures are expected to be within the maximum with the removal of the wheels. allowable levels, wearing such a respirator at all times during brake servicing will help minimize 3. Procedures for Servicing Brakes. exposure. a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be 3. Procedures for Servicing Brakes. equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be HEPA vacuum to loosen and vacuum residue from the brake parts. equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the b. As an alternative procedure, use a catch basin with water and a biodegradable, non- HEPA vacuum to loosen and vacuum residue from the brake parts. phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. b. As an alternative procedure, use a catch basin with water and a biodegradable, non- The solution should be applied with low pressure to prevent dust from becoming airborne. phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. Allow the solution to flow between the brake drum and the brake support or the brake rotor The solution should be applied with low pressure to prevent dust from becoming airborne. and caliper. The wheel hub and brake assembly components should be thoroughly wetted to Allow the solution to flow between the brake drum and the brake support or the brake rotor suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts and caliper. The wheel hub and brake assembly components should be thoroughly wetted to clean with a cloth. suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts c. If an enclosed vacuum system or brake washing equipment is not available, employers may clean with a cloth. adopt their own written procedures for servicing brakes, provided that the exposure levels c. If an enclosed vacuum system or brake washing equipment is not available, carefully clean associated with the employer’s procedures do not exceed the levels associated with the the brake parts in the open air. Wet the parts with a solution applied with a pump-spray enclosed vacuum system or brake washing equipment. Consult OSHA regulations for more bottle that creates a fine mist. Use a solution containing water, and, if available, a details. biodegradable, non-phosphate, water-based detergent. The wheel hub and brake assembly d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for use with components should be thoroughly wetted to suppress dust before the brake shoes or brake asbestos when grinding or machining brake linings. In addition, do such work in an area with pads are removed. Wipe the brake parts clean with a cloth. a local exhaust ventilation system equipped with a HEPA filter. d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA when grinding or e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA machining brake linings. In addition, do such work in an area with a local exhaust ventilation filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, system equipped with a HEPA filter. flammable solvents, or solvents that can damage brake components as wetting agents. e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty flammable solvents, or solvents that can damage brake components as wetting agents. vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet by NIOSH or MSHA for use with asbestos. When you replace a HEPA filter, wet the filter with a fine wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty mist of water and dispose of the used filter with care. vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. by NIOSH or MSHA, to minimize exposure. When you replace a HEPA filter, wet the filter with a Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to fine mist of water and dispose of the used filter with care. vacuum work clothes after they are worn. Launder them separately. Do not shake or use 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. compressed air to remove dust from work clothes. Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to 6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters with care, vacuum work clothes after they are worn. Launder them separately. Do not shake or use such as in sealed plastic bags. Consult applicable EPA, state and local regulations on waste compressed air to remove dust from work clothes. disposal. 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 Regulatory Guidance disposal. References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, Regulatory Guidance 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 References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, regulations that apply to them for further guidance. 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 (Issued 12-04) i 1 Introduction
MASTER CYLINDER ASSEMBLYMeritor WABCO’s Hydraulic Power Brake (HPB) is a braking andvehicle control system for Business Class trucks, Classes 4through 7, and buses that are equipped with hydraulic brakes.The HPB system provides the following functions.앫 Full power brake performance앫 Brake control functions including Anti-Lock Braking System (ABS), Automatic Traction Control (ATC) and Electronic Brake force Distribution (EBD)앫 Optional parking brake control
System Components 4004475aThe HPB system consists of two main components — the HydraulicCompact Unit (HCU) and a dual circuit master cylinder. The HPB Figure 1.3system is also available with an optional parking brake pressuresupply valve. Figure 1.1, Figure 1.2 and Figure 1.3. Hydraulic Compact Unit
Figure 1.1 The HCU consists of an electronic control unit, two independent HCU WITHOUT OPTIONAL POWER electric motors driving two pump systems, two accumulators, a dual PARKING BRAKE SUPPLY VALVE 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. 앫 Two pump motors draw brake fluid from the reservoir to pressurize the accumulators. The motors are not serviceable. 앫 Two gas-filled hydraulic accumulators store energy supplied by the pumps. Accumulators are sealed at the factory and are non-refillable. Accumulators may be replaced without replacing the entire HCU. 4004474b 앫 The ECU processes sensor signals and generates solenoid valve Figure 1.1 commands to reduce, maintain or increase brake pressure for control function. The ECU constantly monitors the pressure in theFigure 1.2
accumulators, using one pressure sensor per brake circuit. The HCU WITH OPTIONAL POWER PARKING BRAKE PRESSURE SUPPLY VALVE ECU may be replaced without replacing the complete HCU. 앫 The optional pressure supply valve controls the Spring-Applied/ Hydraulic Released (SAHR) parking brake. The pressure supply valve is mounted on the HCU behind the accumulator. The pressure supply valve may be replaced without replacing the entire HCU. 앫 The dual circuit HCU reservoir holds the hydraulic brake fluid. The reservoir may be replaced without replacing the entire HCU.
HYDRAULIC COMPACT UNIT MASTER CYLINDER ASSEMBLY WITHOUT PRESSURE SUPPLY VALVE MASTER DUAL CIRCUIT CYLINDER HCU RESERVOIR RESERVOIR RESERVOIR CAP
Figure 1.5 PUMP MOTORS (2) Wheel-End Sensors
4004476a A Meritor WABCO wheel-end sensor is installed at each wheel ACCUMULATORS whose speed is to be monitored. These sensors generate electronic Figure 1.4 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-endMaster Cylinder Assembly maintenance is performed.The dual circuit master cylinder with an integrated relay valveprovides the translation of brake pedal force into hydraulic braking Figure 1.6
pressure, and sends the driver’s demand signal to the HCU. SENSOR SPRINGFigure 1.5. CLIP앫 The foot brake switch provides brake status to the ECU and eliminates the need for a brake light switch.앫 The master cylinder reservoir holds the hydraulic brake fluid.앫 The fluid sensor switch monitors fluid level in the master cylinder reservoir.앫 The master cylinder reservoir and both switches may be WHEEL-END replaced without replacing the entire master cylinder. SENSOR
앫 The master cylinder cap provided by Meritor WABCO contains a 4004479a special gore material that allows the reservoir to breathe, and serves as a filter to help prevent contaminants from getting Figure 1.6 into the reservoir. This is the only cap approved for use with Meritor WABCO HPB. Replacement caps may be obtained from Meritor WABCO.
2 Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04) 1 Introduction
TOOLBOX™ Software Low Pressure HoseTOOLBOX™ Software is a PC-based diagnostics program required This manual contains service information for a low pressure hoseto diagnose HPB system faults. For HPB, version 5.0 or higher is which is not produced by Meritor WABCO but is an integral part ofrequired. The program runs in Windows 98 or higher. TOOLBOX™ the HPB system.is available from SPX Service Solutions, 1-800-328-6657.Figure 1.7. How the HPB System WorksFigure 1.7 Meritor WABCO’s hydraulic power braking system provides the Includes Spanish and French Versions for ABS and HABS energy required to actuate the brakes and control the electronic
PC-based diagnostics and troubleshooting for Meritor WABCO: • Pneumatic ABS (D and E Versions) control the service and park brakes. • Trailer ABS (Easy-StopTM ▲
SOFTWAR • Hydraulic ABS • Hydraulic Power Brake (HPB) The Meritor WABCO HPB system for trucks is illustrated in • Electronic Leveling Valves for Tractors Figure 1.8. A complete HPB system layout, with hydraulic brake WH
Functional DescriptionHydraulic energy is stored in the gas-filled hydraulic accumulators,one for each circuit. When the vehicle’s ignition is turned on, internalpumps are activated and fill both accumulators with hydraulic brakefluid. Two internal sensors, one in each accumulator, measurepressure and the ECU continuously monitors and controls pressure.During normal operation, the ECU actuates two separate powerdrivers for the electric motors, keeping the pressure level within thedesired limits. Two pressure relief valves provide safety againstoverpressure.When the brake pedal is applied, the master cylinder provides ahydraulic signal to the relay valve. Proportional to that signal, theaccumulators release pressure to the brake calipers. When thepedal is released, brake fluid returns from the brake calipers to thereservoir, and line pressure is reduced to zero.For ABS, wheel pressure is individually modulated by eightintegrated ABS solenoid valves in the ECU.For ATC, the normally closed ATC solenoid valve in the ECU isactuated and hydraulic energy is supplied to the sensed wheel.At the same time, the normally open ATC valve is actuated toprevent fluid flow back into the reservoir. The brake pressure is thenmodulated by the corresponding ABS solenoid valves.
4 Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04) Figure 2.1 2 Wiring Diagram
Figure 2.1 WIRING DIAGRAM FOR MULTIPLEX VEHICLES WITH POWER BRAKE OPTION
P P PUMP– ATC–SOLENOIDS WHEEL PRESSURE MODULATION SOLENOIDS PUMP– MOTOR 1 MOTOR 2
ELECTRONIC CONTROL UNIT 2-PIN CONNECTOR 31-PIN CONNECTOR
2 1 4 5 7 16 18 17 19 1 6 11 10 9 31 26 14 15 3 24 29 25 30 23 28 22 27 diagram for multiplex vehicles appears in Figure 2.1.
2 1 The Meritor WABCO HPB electronic control unit interface wiring
IGNITION GROUND PIN 7 IGNITION 2x0.75 mm2 TWISTED
2x0.75 mm2 TWISTED 2x0.75 mm2 TWISTED
BRAKE SWITCH 2x0.75 mm2 TWISTED
* PUMP MOTOR 2 SUPPLY * PUMP MOTOR 2 GROUND 560R
* PUMP MOTOR 1 SUPPLY 1K
* PUMP MOTOR 1 GROUND 2 2 GRD 3K 27K STUD 1 3 DIAGNOSE "A" ACC. SAE J1587 DIAGNOSE "B" CAN HIGH ACC. SAE J1939 CAN LOW BRAKE LIGHT SIGNAL
GRD STUD 2 PARKING BRAKE 30A 30A 30A 5A – + GRD +12V STUD 3 BATTERY FEED
NOTES: * WIRE SIZE AWG 12 (SAE J 1128 TYP: GXL–CABLE) RESPECTIVELY MIN. 3 MM2: ELECTRIC CABLES WITHOUT MARKS: AWG 18 (SAE J 1128 TYP: TXL–CABLE) RESPECTIVELY 1 MM2 TOTAL RESISTANCE INCLUDING CRIMP = 0.04 OHMS. BLADE TYPE FUSES CORRESPONDING TO ISO/DIS 8820 CORRESPONDS TO AN OVERALL LENGTH OF 6 METERS.
Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04)5 2 Wiring Diagram3 Troubleshooting and Testing
This section contains information for testing the HPB system with This screen provides icons and pull-down menu task selections.TOOLBOX™ Software, and for performing standard component and It also provides information about the current status of Meritorelectrical tests. WABCO HPB. Figure 3.1. Figure 3.1
Meritor WABCO TOOLBOXTM Software ECU information is read once from the ECU and does not change. All other information (e.g., wheel sensors, voltages and faultUse TOOLBOX™ Software to verify the activation of various system information) is read and updated continuously.components. Display앫 Turn valves, pump and retarder relay on and off (Valve Activation Menu) Select Display from the HPB Main Screen. A pull-down menu will appear. Figure 3.2.앫 Turn indicator lamps on and off (Miscellaneous Output Activation Menu) Figure 3.2
NOTE: For complete instructions for using this program, refer to theUser’s Manual, TP-99102. Contact Meritor WABCO at800-535-5560 for information about TOOLBOX™ Software.
Hydraulic Power Brake Menus and ToolbarsSelect Hydraulic ABS from the TOOLBOX™ Main Menu.TOOLBOX™ senses the type of ECU being used and displays theHPB Main Screen.
6 Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04) 3 Troubleshooting and Testing
Wheel Speed 4004462aSelect Wheel Speed to display the Wheel Speed screen.Figure 3.4. Figure 3.5
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.
8 Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04) 3 Troubleshooting and 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 3.12.
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.
4004469a 4004471a Figure 3.12 Figure 3.14NOTE: The status bar on the HPB Main Menu reflects the currentATC status (enabled, disabled or not available). Relay is an automatic default and cannot be de-selected. It indicates the ECU has memorized the installed retarder relay. Once the ECUMiscellaneous Outputs has seen a retarder, it expects to see it every time the vehicle isSelect Miscellaneous Outputs to display the Activate powered up.Miscellaneous Outputs test screen. Figure 3.13. Standard TestingNOTE: Use TOOLBOX™ Software to test the following components:Retarder Relay, Brake Light Relay, Supply Valve, Cut-Off Valve, ABS Test Equipment: Volt-Ohm Meter (VOM)Lamp, Traction Lamp, Brake Warning, Pump Front, Pump Rear, Use of a VOM with automatic polarity sensing is recommended. ThisBuzzer. eliminates the concern of the polarity of the meter leads duringFigure 3.13 voltage measurements.
System Requirements and Component Tests Tire Size Range 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%. Calculate the tire size with the following equation:
10 Meritor WABCO Maintenance Manual MM-0401 (Issued 12-04) 3 Troubleshooting and Testing
CAUTION Vehicle Test DriveWhen troubleshooting or testing the ABS system, do not After replacing an HPB component, test drive the vehicle as follows:damage the connector terminals. 1. Turn ignition ON.Voltage Check NOTE: Depending on the vehicle, the ATC lamp may beVoltage must be between 10 and 16 volts for the 12-volt hydraulic labeled differently and some vehicles may not have an ATCABS to function correctly. lamp. Refer to the vehicle specification sheet for labelCheck the voltage as follows. designation.
1. Turn the ignition ON. 2. Check the vehicle dash lamps:2. Check for correct voltage: 앫 All of the dash lamps for HPB come on briefly 31-Pin Harness: (approximately three seconds) for a bulb check, then go off. This indicates the system is O.K. 앫 Pins 1 and 6 for ignition and ground 앫 ABS and ATC lamps do not go off. The system is looking for 앫 Pins 16 and 18 for pump motor 2 wheel speed. Drive the vehicle at speeds of 10-15 mph 앫 Pins 17 and 19 for the solenoid valve (16-24 km/h). The ABS and ATC lamps will go off. This indicates the system is O.K. 2-Pin Power Connector: 앫 ABS and ATC lamps do not go off after the vehicle reaches 앫 Pins 2 and 1 for pump motor 1 a speed of 10-15 mph (16-24 km/h). This indicates there is If voltage is not between 10 and 16 volts, verify the wiring a system fault. Perform vehicle diagnostics and make all of connections. Make corrections as required. the necessary repairs, including appropriate bleed procedures, before returning the vehicle to service.Standard Component Testing 3. Drive the vehicle for a short distance. Make gentle brake applications to verify brake performance.Indicator LampsIf 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 allABS fuses or circuit breakers and replace if necessary. Afterchecking the indicator lamps, make repairs as necessary.
Read and observe all Warning and Caution hazard alert messages inthis publication. They provide information that can help prevent Hydraulic Compact Unitserious personal injury, damage to components, or both. CAUTION Thoroughly clean the area around the HCU fittings before WARNING beginning the removal procedure to avoid contaminating theTo prevent serious eye injury, always wear safe eye protection system. As hoses and brake lines are removed, plug all openwhen you perform vehicle maintenance or service. ports and lines. Contamination may prevent the HPB system from operating correctly.Release all air from the air systems before you remove anycomponents. Pressurized air can cause serious personal NOTE: The following general guidelines are provided to facilitate theinjury. safe removal of the HCU from the vehicle.The full power brake system is a pressurized system that 앫 Two people are needed to perform this procedure.achieves pressures of up to 2320 psi. This pressure is notreduced by switching the ignition off or removing battery 앫 For the HCU drain procedure in Step 11, TOOLBOX™ Softwarepower. Prior to servicing this system, the depressurization version 5.4 or higher is required. If you do not have this versionprocedures must be performed exactly as presented. Failure to of TOOLBOX™ Software, please contact the ArvinMeritordepressurize the system may result in personal injury or Customer Service Center for additional information.death. 앫 In some vehicles it may be necessary to move non-HPB system components, such as the air tank, in order to access the HPB CAUTION part. If this is necessary, refer to the vehicle manufacturer’sThe HPB hydraulic power brake system is a complex device manual for information before moving the component.that provides optimum efficiency and operation. If the systemsustains damage, or a component malfunctions and requires 앫 HPB systems may include automatic parking brakes. If yourreplacement, the replacement procedures provided by Meritor vehicle is equipped with manual parking brakes, refer to theWABCO must be followed exactly with the associated steps manual parking brake procedures. To determine the type ofperformed in the order presented. parking brake on the vehicle, refer to the vehicle specification sheet.Hydraulic brake fluid is a caustic substance. Contact with the 앫 Bleed the brake and master cylinder circuits. Bleed procedureshydraul