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