Pinpoint Test C: DTC C1095
Anti-Lock Control
Pinpoint Tests
Pinpoint Test C: DTC C1095
Refer to Wiring Diagrams Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The operating voltage required for the ABS module to operate the hydraulic pump is in a range between 10 and 16 volts.
Fused battery voltage for hydraulic pump motor operation is supplied to the ABS module by Battery Junction Box (BJB) fuse 9 (40A) along circuit SBB09 (RD). Ground for all ABS operations is provided along circuit GD122 (BK).
The ABS module performs 2 different tests to determine pump motor condition. The first test is done when the ignition key is turned to the ON position and is used to test for a pump motor that may be locking up. The ABS module commands the Hydraulic Control Unit (HCU) pump motor on for 100 ms (±6 ms) and then commands the pump motor off. Once the pump motor is commanded off, it will generate a small amount of voltage. Six milliseconds after commanding the pump off, the ABS module will read the voltage that is being generated by the pump motor. If the voltage indicates the motor is spinning at less than 500 rpm, the motor may be locking up.
The second test is used to check for an open circuit and a short to voltage. Two seconds after the most recent (successful) pump motor off command, the ABS module will read the voltage that is being generated by the pump motor. If the voltage generated remains greater than 0.75 volt for more than 50 ms (±6 ms) after the off command, then a short to voltage may exist. If there is no voltage generated by the pump motor, then an open circuit condition may exist.
- DTC C1095 (ABS Hydraulic Pump Motor Circuit Failure) - If during normal operation or the on-demand self test the ABS module detects a short to voltage or ground, a locked pump motor (must be detected 4 times) or an internal failure of the ABS module (short to voltage or ground), DTC C1095 will be set.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- HCU
- ABS module
PINPOINT TEST C: DTC C1095
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
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C1 CHECK FOR ABS MODULE DTCs
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Clear ABS Module DTCs.
- Enter the following diagnostic mode on the scan tool: Self Test - ABS Module.
- Carry out the ABS module self-test. Retrieve and record all ABS module DTCs.
- Is DTC C1095 present?
Yes
GO to C2.
No
For all other DTCs, GO to the ABS Module DTC Chart. ABS Module DTC Chart
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C2 CHECK THE ABS PUMP MOTOR
- Ignition ON.
- Is the ABS pump motor running all the time?
Yes
INSTALL a new ABS module and HCU. REFER to Anti-Lock Brake System (ABS) Module Service and Repair and
Hydraulic Control Unit (HCU) Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
GO to C3.
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C3 CHECK THE ABS MODULE HYDRAULIC PUMP MOTOR (PMP_MTR) ACTIVE COMMAND
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
- Toggle the PMP_MTR active command ON.
- Does the hydraulic pump motor run for approximately 2 seconds?
Yes
TOGGLE the PMP_MTR active command OFF. GO to C4.
No
TOGGLE the PMP_MTR active command OFF.
CLEAR the DTCs. CYCLE the ignition switch. RETRIEVE and RECORD the ABS module DTCs.
If DTC C1095 is retrieved, GO to C5.
For all other DTCs, GO to the ABS Module DTC Chart. ABS Module DTC Chart
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C4 CHECK FOR RETURNING ABS MODULE DTCs
- Drive the vehicle (brakes must not be applied) above 32 km/h (20 mph).
- Enter the following diagnostic mode on the scan tool: Self Test - ABS Module.
- Retrieve and record the ABS module DTCs.
- Is DTC C1095 present?
Yes
INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
For all other ABS module DTCs, GO to the ABS Module DTC Chart. ABS Module DTC Chart
If no DTCs are present, the system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.
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C5 CHECK THE VOLTAGE TO THE ABS MODULE
- Ignition OFF.
- Disconnect: ABS Module C135.
- Measure the voltage between ABS module C135-14, circuit SBB09 (RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C6.
No
VERIFY BJB fuse 9 (40A) is OK. If OK, REPAIR circuit SBB09 (RD).
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
CLEAR the DTCs. REPEAT the self-test.
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C6 CHECK THE ABS MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between ABS module C135-26, circuit GD122 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to C7.
No
REPAIR circuit GD122 (BK). CLEAR the DTCs. REPEAT the self-test.
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C7 CHECK FOR CORRECT ABS MODULE OPERATION
- Check ABS module C135 for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS C135.
- Make sure the ABS connector is fully seated, then operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new ABS module and HCU. REFER to Anti-Lock Brake System (ABS) Module Service and Repair and
Hydraulic Control Unit (HCU) Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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