ABS C0268 pump motor circuit shorted

ISMAEL064

MEMBER
2004 CHEVROLET AVALANCHE
V8
4WD
AUTOMATIC
165,000 MILES

Light on ABS problem. I changed bearing hug wheel but still on when run the truck 10 miles/hour. I erased the code and come back after run at the speed. And my truck when is running light on ABS but I hear a noise like forced and with problems to run more faster sometime I think is the transfer case module. Please help me I use my truck, the snow came and I need drive to my work.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good evening,

This code is for the pump itself. In most cases, it is the ABS pump that has failed.

Roy

Circuit Description
The EBCM applies the ground needed for pump motor activation. The low side of the pump motor has a feedback circuit to the EBCM. When the pump motor is commanded OFF and at rest, feedback voltage is high. When the pump motor is winding down after being commanded ON and then OFF, feedback voltage is low. The EBCM monitors this feedback voltage in order to determine if the motor is functioning properly.

Conditions for Running the DTC
The ignition is ON.
The vehicle speed is greater than 6 km/h (4 mph).

Conditions for Setting the DTC
The EBCM detects any of the following conditions:
An open or shorted pump motor
An open or shorted pump motor driver circuit
A seized pump motor

Action Taken When the DTC Sets
The EBCM disables the ABS.
The ABS indicator turns ON.

Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. It is imperative that the vehicle be driven to attempt to reset the DTC. Using the scan tool to perform a function test may not produce the same result, and therefore may cause misdiagnosis of the vehicle.
7. This step tests if the EBCM is capable of activating the ABS pump motor.
8. A shorted ABS pump motor may damage the EBCM. It is imperative that the steps in the table be followed in order to prevent damage to a replacement EBCM.

Removal Procedure

Caution: Refer to Battery Disconnect in Service Precautions.

Important: After installation, calibrate the new EBCM to the tire size that is appropriate to the vehicle.

1. Disconnect the negative battery cable.
2. Raise and suitably support the vehicle. Refer to Vehicle Lifting.

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Important: The area around the EHCU MUST be free from loose dirt to prevent contamination of disassembled ABS components.

3. Thoroughly wash all contaminants from around the EHCU (1).
4. Disconnect the electrical connectors from the EBCM.
5. Loosen or remove 3 bolts (4) securing the EHCU mounting bracket (3) to the frame rail (5).

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6. Gently move the EHCU down enough to remove the four mounting screws that fasten the EBCM (2) to the BPMV (1).
7. Remove the EBCM (2) from the BPMV(1). Removal may require a light amount of force.
8. Clean the BPMV to EBCM mounting surfaces with a clean cloth.

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