Pinpoint Test F: DTCs C0020:01, 1C and 71
Anti-Lock Control - Traction Control and Stability Assist
Pinpoint Tests
Pinpoint Test F: DTCs C0020:01, 1C and 71
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The ABS module uses an internal solid state switch to operate the ABS pump motor. The ABS module will test the ABS pump motor by activating it for 30 milliseconds. While the pump motor is being activated, the ABS module monitors the voltage drop across the ABS pump motor solid state switch and the amount of current the ABS pump motor draws through the solid state switch. If the voltage drop is too high or if the ABS pump motor is drawing too much current, the ABS module will set a DTC. After 30 milliseconds have passed, the ABS module will stop applying voltage to the pump motor and observe the voltage that the spinning ABS pump motor is generating. The voltage generated by the motor indicates how fast the motor is spinning. A voltage that is too low indicates that the motor is not spinning freely and a DTC will set.
Fused battery voltage from Battery Junction Box (BJB) fuse 12 (30A) along circuit 30-CF13 (RD) is used by the ABS module to power the ABS pump motor. The ABS module provides ground for the ABS pump motor from 91-CF13 (BK/BU). Insufficient power or ground along from these circuits will cause multiple DTCs to set.
- DTC C0020:01 (ABS Pump Motor Control: General Electrical Failure) - If there is a loss of voltage to the pump motor within the Hydraulic Control Unit (HCU), if the voltage supply is internally shorted to ground, or if the HCU internal pump motor ground circuit is open or has high resistance, this DTC will set.
- DTC C0020:1C (ABS Pump Motor Control: Circuit Voltage Out Of Range) - If the voltage supplied to the ABS module is less than 7.3 volts, if there is an open or high resistance on the ABS pump motor circuit between the ABS module and the HCU, or if the ABS module is faulted internally, this DTC will set.
- DTC C0020:71 (ABS Pump Motor Control: Actuator Stuck) - If the ABS module detects that the ABS pump motor is not rotating when it is commanded to run, this DTC will set.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- HCU
- ABS module
PINPOINT TEST F: DTCs C0020:01, 1C AND 71
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
NOTE: This vehicle has an in-line test connector C126 which may make circuit testing easier in certain situations.
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F1 CHECK THE DTCs FROM THE SELF-TEST
- Review the DTCs retrieved during Inspection and Verification.
- Was DTC C0020:01 the only DTC retrieved?
Yes
INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) Service and Repair.
No
If other DTCs were retrieved, GO to F2.
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F2 CHECK THE PUMP MOTOR (PMP_MOTOR) ACTIVE COMMAND
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module .
- Toggle the PMP_MOTOR active command ON.
- Does the ABS pump motor run for approximately 2 seconds?
Yes
TOGGLE the PMP_MOTOR active command OFF. CLEAR the DTCs. DRIVE the vehicle at speeds greater than 20 km/h (12 mph). RETRIEVE the DTCs. If DTCs C0020:1C or 71 are retrieved, GO to F5. For all other ABS module DTCs, GO to the ABS Module DTC Chart. Anti-Lock Control - Traction Control and Stability Assist
No
TOGGLE the ABS module pump motor OFF active command. GO to F3.
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F3 CHECK THE PUMP MOTOR VOLTAGE SUPPLY TO THE ABS MODULE
- Ignition OFF.
- Disconnect: ABS Module C155 .
- Ignition ON.
- Measure the voltage between ABS module C155-1, circuit 30-CF13 (RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to F4.
No
VERIFY that BJB fuse 12 (30A) is OK. If OK, REPAIR circuit 30-CF13 (RD).
If the fuse is not OK, REFER to the Wiring Diagrams to identify the cause of the circuit short. Diagrams By Number
CLEAR the DTCs and REPEAT the self-test.
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F4 CHECK THE ABS MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between ABS module C155-47, circuit 91-CF13 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to F5.
No
REPAIR circuit 91-CF13 (BK/BU). CLEAR the DTCs. REPEAT the self-test.
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F5 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect: In-line Connector C126 .
- Check ABS module C155 and in-line connector C126 for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: In-line Connector C126 .
- Connect: ABS Module C155 .
- Make sure the connector is seated correctly, then operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new Hydraulic Control Unit (HCU). REFER to Hydraulic Control Unit (HCU) Service and Repair. TEST the system for normal operation.
CLEAR the DTCs. DRIVE the vehicle at speeds greater than 20 km/h (12 mph). REPEAT the self-test.
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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