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Pinpoint Test A: DTCs C0020:13, C0020:71




Anti-Lock Control

Pinpoint Test A: DTCs C0020:13, C0020:71

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 tests 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 sets a DTC. After 30 milliseconds have passed, the ABS module stops applying voltage to the pump motor and observes the voltage that the spinning ABS pump motor is generating. The voltage generated by the motor indicates how fast the motor is spinning. Voltage that is too low indicates that the motor is not spinning freely and a DTC sets.

The ABS module uses fused battery voltage from Battery Junction Box (BJB) to power the ABS pump motor. The ABS module provides ground for the ABS pump motor. Insufficient power or ground along the circuits causes multiple DTCs to set.

- C0020:13 (ABS Pump Motor Control: Circuit Open) - this DTC sets if the voltage supplied to the ABS module is less than 10 volts, if there is an open or high resistance on the ABS pump motor circuit between the ABS module and the Hydraulic Control Unit (HCU), or if the ABS module is faulted internally.
- C0020:71 (ABS Pump Motor Control: Actuator Stuck) - this DTC sets 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
- Hydraulic pump motor
- ABS module

PINPOINT TEST A: DTCs C0020:13 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.

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A1 CHECK THE PUMP MOTOR (PMP_MTR) ACTIVE COMMAND

- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ABS Module DataLogger.
- Toggle the PMP_MTR active command ON.
- Listen for the ABS pump motor noise, does the ABS pump motor run for approximately 2 seconds?

Yes
TOGGLE the PMP_MTR active command OFF. CLEAR the DTCs. DRIVE the vehicle at speeds greater than 20 km/h (12 mph). RETRIEVE the DTCs. If DTC C0020:13 or 71 is retrieved, GO to A5. For all other ABS module DTCs, GO to the DTC Chart . If no ABS module DTCs are retrieved, the system is operating correctly at this time. [1][2]Diagnostic Trouble Code Descriptions

No
TOGGLE the PMP_MTR active command OFF. GO to A2.

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A2 CHECK THE ABS MODULE GROUND EYELET

- Ignition OFF.
- Remove the bolt retaining G107/G108 at the inner RF fender.
- Clean the chassis 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 Self Test CMDTCs.
- Is the concern still present?

Yes
GO to A3.

No
The concern was caused by a loose or corroded connector. CLEAR the DTCs. REPEAT self-test.

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A3 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 SBB01 (RD), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to A4.

No
VERIFY that BJB fuse 1 (40A) is OK. If OK, REPAIR circuit SBB01 (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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A4 CHECK THE ABS MODULE GROUND CIRCUIT FOR AN OPEN

NOTE: Failure to disconnect the battery when instructed results in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.

- Ignition OFF.
- Disconnect: Battery Cable - Negative.
- Measure the resistance between ABS module C135-47, circuit GD123 (BK/GY), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to A5.

No
REPAIR circuit GD123 (BK/GY) for an open circuit. CLEAR the DTCs. REPEAT the self-test.

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A5 CHECK FOR CORRECT ABS MODULE OPERATION

- Connect: Battery Cable - Negative.
- Check ABS module C135 for:

- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C135.
- 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 Hydraulic Control Unit (HCU) Service and Repair.

CLEAR the DTCs. DRIVE the vehicle at speeds greater than 20 km/h (12 mph). 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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