hydraulic anti-lock braking system for trucks, buses and motor homes
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Hydraulic Anti-LockBraking System
For Trucks, Buses andMotor Homes
Hydraulic Anti-LockBraking System
For Trucks, Buses andMotor Homes
The World Leader in ABS for Heavy-Duty Commercial
Vehicles
Offers State-of-the-Art Systems
The World Leader in ABS for Heavy-Duty Commercial
Vehicles
Offers State-of-the-Art Systems
In Production Since 1989 with Range RoverDevelopment Started in 1985
Over 1,000,000 Systems Produced
Hydraulic ABS
Hydraulic ABS
• Required on vehicles produced after March 1, 1999
• All vehicles over 10,000 lbs GVW
• Minimum 4S / 3M system
Federal MandateFederal Mandate
Hydraulic ABS
• Enhance stability
• Maintain steerability
• Improve stopping distances
• Stabilize insurance costs
• Reduction in number and severity of accidents
Reasons For ABSReasons For ABS
Features of Hydraulic ABSFeatures of Hydraulic ABS
Hydraulic ABS
• Robust design inspired by heavy-duty pneumatic ABS (sensors, sealing, etc.)
• Optimized performance of retarders
• Optimized performance of wide range of tire sizes (more than one ECU)
• Both cab and frame mounted ECU’s
Modulator Assembly Connector Pin Assignment
MAIN GROUNDFOR MODULATOR ASSEMBLY
PinNumber
CircuitDescription
PinNumber
CircuitDescription
1
2
3
4
5
6
7
Outlet Valve RL
Inlet Valve RL
- - - - - - -
Inlet Valve FR
Outlet Valve FR
- - - - - - -
- - - - - - -
8
9
10
11
12
13
Reference Ground
- - - - - - -
Outlet Valve RR
Inlet Valve RR
Inlet Valve FL
Outlet Valve FL
Identifying D-Version Hydraulic ABS Codes
• Loose or burned out bulb
• Voltage not within
• acceptable range (9.5 to 14 volts DC)
• Repair or replace lamp bulb• Measure voltage, check connections, make
necessary repairs
ABS indicator lamp does not come on
Check ABS indicator lamp for blink codeABS indicator lamp comes on briefly then goes out
No further action requiredIf ONE blink code is displayed
System OK
Go to Step 2If ONE blink code other than 1-1 is continuously displayed
System fault exists
Go to Step 3If a series of codes are displayed
Stored faults in system
Step 1
Turn ignition key ON. DO NOT turn engine on. Press Blink Code Switch once, then release
Step 2
Repair fault
• Find blink code on TABLE C*• Turn off the ignition• Repair the fault• Clear the fault (go to Step 3)
No further action requiredABS indicator lamp displays blink code 1-1, then goes OFF
System OKStep 3
Clear fault
Turn ignition key ON. DO NOT turn engine on. Press Blink Code Switch. HOLD FOR 3 SECONDS. RELEASE
Drive the vehicle at a speed of 4 mph (6 km/h). Once the ECU senses wheel speed, the lampwill go OFF
If the ABS indicator lamp displays blink code 1-1, goes OFF, then comes back on and stays ON
System looking for wheel speed. This occurs after a sensor fault
Response Status Action
If you receive a blink code that is not identified in TABLE C, contact the Meritor Customer Support Center at 800-535-5560*
Ignition Key ON to determine ABS blink code fault
IV
Ignition Key OFF to test system (except where noted)
1 2 3 4 5Correct Volt Ohm Meter Readings
FaultCode Problem Area Connector
Pins to be Tested Action
1-1 System OK None required
2-1 RIGHT FRONTSolenoid valve (inlet or outlet valve) failure in modulator, wiring harness or inside ECU
2-1 RIGHT FRONTSolenoid valve (inlet or outlet valve) failure in modulator, wiring harness or inside ECU
2-1 RIGHT FRONTSolenoid valve (inlet or outlet valve) failure in modulator, wiring harness or inside ECU
2-1 RIGHT FRONTSolenoid valve (inlet or outlet valve) failure in modulator, wiring harness or inside ECU
2-1 RIGHT FRONTSolenoid valve (inlet or outlet valve) failure in modulator, wiring harness or inside ECU
15-pin
15-pin
15-pin
15-pin
15-pin
IV
IV
IV
IV
3 to chassis ground
5 and 3
2 and 3
1 and 3
8 and 3
OV
OV
OV
OV
4 and 3
1 and 3
10 and 3
7 and 3
0 volt
Inlet valve: 6.5 + 0.5 ohmsOutlet valve: 3.5 + 0.5 ohms
Check electrical resistance of affected valve wiring to ground at ECU vehicle connector and at modulator plug
Check voltages at wiring harness and connectors. Voltage of ground connector should be approximately 0 volts. Make necessary repairs
Check ABS ground connections. Make necessary repairs
OV= Inlet Valve = Outlet Valve
D Version Hydraulic ABS Blink Codes
Ignition Key ON to determine ABS blink code fault Ignition Key OFF to test system (except where noted)
1 2 3 4 5Correct Volt Ohm Meter Readings
FaultCode Problem Area Connector
Pins to be Tested Action
3-1 RIGHT FRONTsensor - Air gap
9-pin
Check for sensor adjustment. Check for excessive wheel bearing endplay. Repair or replace as needed
3-2 LEFT FRONTsensor - Air gap
3-3 RIGHT REARsensor - Air gap
3-4 LEFT REARsensor - Air gap
9-pin
9-pin
9-pin
Greater than .2 volts AC at 30 RPM
(Rotate wheel 1/2 revolution per second)
4 and 5
1 and 2
3 and 6
7 and 8
4-1 RIGHT FRONTsensor - Electrical Fault
9-pin 4 and 5
4-2 LEFT FRONTsensor - Electrical Fault
9-pin 1 and 2
4.3 RIGHT REARsensor - Electrical Fault
9-pin 3 and 6
4.4 LEFT REARsensor - Electrical Fault
9-pin 7 and 8
5.1 RIGHT FRONTwheel - Erratic wheel speed
5.2 LEFT FRONTwheel - Erratic wheel speed
5.3 RIGHT REARwheel - Erratic wheel speed
5.4 LEFT REARwheel - Erratic wheel speed
500-2000 ohms
Check electrical resistance of affected sensor and wiring at ECU connector and at harness plugs. Repair or replace as needed
Check for tire size mismatch or tooth wheel difference. Check sensor cable and connector for intermittent contact. Repair or Replace as needed
Verify proper connections to relay. (See wiring diagram)
Check bulb. Repair or replace as needed.70
7.3 Retarder Relay
7.4 ABS warning lamp
D Version Hydraulic ABS Blink Codes (Con’t.)
Ignition Key ON to determine ABS blink code fault Ignition Key OFF to test system (except where noted)
1 2 3 4 5Correct Volt Ohm Meter Readings
FaultCode Problem Area Connector
Pins to be Tested Action
7-7 Recirculation pump does not switch off
18-pin 8 and 12
8 and 12
0 volt Check the recirculation pump wiring, the pump relay and fuse and pump connections. Repair or replace as needed
Recirculation pump does not switch on (low level with act)
ORTURN IGNITION ON12 volts DC
7-8 Recirculation pump does not switch off
18-pin Link pins 2 and 8
TURN IGNITION ON
Excessive current failure. If pump does not run when pins are linked, replace modulator assembly
8-1 No voltage to ABS solenoid valves
18-pin 1 and 2 12 volts DC TURN IGNITION ON
Check the valve relay, fuse and wiring. Repair or replace as needed
8-2 Continuous supply to ECU with ignition off
18-pin 5 and 12 0 volts Check for proper wiring connections. Make necessary repairs
8-3 Internal ECU fault Replace ECU
D Version Hydraulic ABS Blink Codes (Con’t.)
Benefits To The User• Stops shorter on most surfaces• Stability• Ability to steer
Steering Wheels Locked
PLOW OUTPLOW OUT(Can’t Steer)
Rear Wheels Locked
FISH TAILFISH TAIL(Back End Swings Out)
Hydraulic ABS
Electrical System - 4 Channel System Layout
4 ChannelECU
+ 12 Volts
Ground
ABS ValveAssembly
Hydraulic ABS
Hydraulic System Layout
HydraulicBrake Lines
Hydraulic ABSValve Assembly
Valve Assemblyto ECU Cable
Power Plug forValve Assembly
Motor
HydraulicBrake Lines
Hydraulic Anti-lock Brake System
76
Closed Loop Control SystemSensor
ToothWheel
ECU
Hydraulic ABS Valve Assembly
PumpMotor
RearAxle
FrontAxle
Hydraulic ABS
Valve AssemblyHydraulic Layout
CheckValve (4)
Solenoid (4)NO
NC
Accumulator
NO = Normally OpenNC = Normally Closed
Solenoid (4)
Valve AssemblyPressure IncreaseHydraulic Layout
Hydraulic ABS
PumpMotor
RearAxle
FrontAxle
Hydraulic ABS
PumpMotor
RearAxle
FrontAxle
Valve AssemblyPressure DecreaseHydraulic Layout
Hydraulic ABS
PumpMotor
RearAxle
FrontAxle
Valve AssemblyPressure Hold
Hydraulic Layout
Hydraulic ABS Cab MountECU Wiring Diagram
Hydraulic ABS Frame MountECU Wiring Diagram
Hydraulic ABS
• Blink code diagnostics
• PC diagnostics
• Maintenance manual no. 39
• Meritor customer service center1-800-535-5560
• On-site training
DiagnosticsDiagnostics
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