Pinpoint Test C: DTCs C0020:12, C0020:15 and C0020:71
Anti-Lock Control
Pinpoint Test C: DTCs C0020:12, C0020:15 and C0020:71
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information [1][2]Diagrams By Number.
Normal Operation
When the ignition key is turned to the ON position, the ABS module commands the Hydraulic Control Unit (HCU) pump on for 100 ms (±6 ms) and is then commanded off. After 6 ms, the ABS module reads the voltage that is being generated by the HCU (Hydraulic Control Unit) pump. If the voltage indicates the motor is spinning at less than 500 rpm, there may be a locked motor. If this condition is detected 4 times, DTC C0020:12 sets. The pump motor is checked for an open circuit 2 seconds after the most recent successful pump motor off command. If the pump motor feedback remains greater than 0.75 volt for more than 50 ms (±6 ms) after these conditions have been met, DTC C0020:15 sets.
- DTC C0020:12 (ABS Pump Motor Control: Circuit Short To Battery)- sets in continuous memory and on-demand when the motor driver feedback voltage is less then battery voltage, that indicates an open driver or supply condition where the battery voltage is adjusted to the minimal threshold for the motor supply.
- DTC C0020:15 (ABS Pump Motor Control: Circuit Short To Battery Or Open)- sets in continuous memory and on-demand if the ABS pump feedback voltage is greater than 0.75 volts for more than 50 ms after the pump motor has been commanded off for 2 seconds or more, if there is an open or high resistance on the ABS pump motor circuit between the ABS module and the HCU (Hydraulic Control Unit) , or if the ABS module is faulted internally.
- DTC C0020:71 (ABS Pump Motor Control: Actuator Stuck)- sets in continuous memory and on-demand if the ABS module detects that the ABS pump motor is not rotating when it is commanded to run.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- HCU (Hydraulic Control Unit)
- ABS module
PINPOINT TEST C : DTCs C0020:12, C0020:15 AND C0020:71
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed results in false resistance readings.
C1 CHECK THE PUMP MOTOR (PMP_MOTOR) ACTIVE COMMAND
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ABS Module DataLogger.
- Toggle the PMP_MOTOR active command ON.
Listen for the ABS pump motor noise, does the ABS pump motor run for approximately 2 seconds?
Yes
GO to C2.
No
TOGGLE the PMP_MOTOR active command OFF. GO to C3.
C2 CHECK FOR FAULT REPEATABILITY
- Drive the vehicle at speeds greater than 20 km/h (12 mph).
- Enter the following diagnostic mode on the scan tool: ABS Module Self Test.
Are DTCs C0020:12, C0020:15 or C0020:71 retrieved?
Yes
GO to C3.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
C3 CHECK THE ABS MODULE GROUND EYELET AT THE CHASSIS
- Ignition OFF.
- Remove the bolt retaining GD120, in the engine compartment, LH side front.
- Clean the body mating surface and ground eyelets.
- Install the ground eyelet to the chassis with the retaining bolt.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ABS Module Self-Test.
Are DTCs C0020:12, C0020:15, C0020:71 retrieved?
Yes
GO to C4.
No
The concern was caused by a loose or corroded connector. CLEAR the DTCs. REPEAT self-test.
C4 CHECK THE PUMP MOTOR VOLTAGE SUPPLY TO THE ABS MODULE
- Ignition OFF.
- Disconnect: ABS Module C135.
- Measure the voltage between ABS module C135-1, circuit SBB08 (VT/RD), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to C5.
No
VERIFY that BJB (Battery Junction Box) fuse 8 (40A) is OK. If OK, REPAIR circuit SBB08 (VT/RD). If not OK, REFER to the Wiring Diagrams to identify the cause of the circuit short [1][2]Diagrams By Number.
CLEAR the DTCs. REPEAT the self-test.
C5 CHECK THE ABS MODULE GROUND CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between ABS module C135-13, circuit GD120 (BK/GN), harness side and ground and the ABS module C135-38, circuit GD120 (BK/GN), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to C6.
No
REPAIR circuit GD120 (BK/GN) for an open circuit. CLEAR the DTCs. REPEAT the self-test.
C6 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect: ABS Module.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect: ABS Module.
- 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 ABS module. REFER to Anti-Lock Brake System (ABS) Module . GO to C7.
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.
C7 CHECK FOR FAULT REPEATABILITY
- Drive the vehicle at speeds greater than 20 km/h (12 mph).
- Enter the following diagnostic mode on the scan tool: ABS Module Self Test.
Are DTCs C0020:12, C0020:15, C0020:71 retrieved?
Yes
INSTALL a new HCU (Hydraulic Control Unit). REFER to Hydraulic Control Unit (HCU) . TEST the system for normal operation.
No
The repairs are complete. The system is operating correctly at this time.