Antilock Braking System (ABS)

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CIRCUIT DESCRIPTION
The pump motor relay closes and provides voltage to operate the pump when it is grounded by the EBTCM. Once the motor circuit is energized a pump on signal is sensed by the EBTCM to verify pump operation.

CONDITIONS FOR SETTING THE DTC
Voltage is present at the pump motor for 5 seconds without pump motor relay activation from the EBTCM.

Voltage is NOT present at the pump motor within 60 milliseconds After the EBTCM requests pump motor relay activation.

The pump motor runs for longer than 100 milliseconds After the EBTCM requests pump motor cancellation.

The motor GND circuit is open.
There is a pump motor malfunction.

ACTION TAKEN WHEN THE DTC SETS
- A malfunction DTC is stored.
- The ABS and the TO indicator lamps are turned on.
- The ABS and the TCS are disabled.

CONDITIONS FOR CLEARING THE DTC
- The condition for DTC is no longer present. The scan tool Clear DTCs function is used.
- 100 drive cycles have passed with no DTCs detected.

DIAGNOSTIC AIDS
The Return Pump Relay Test, located in Special Functions of the scan tool can be used to determine if the pump circuit is operating properly. This test can only be performed if DTC 35 is not currently set.

Perform a thorough inspection of the wiring. Perform a thorough inspection of the connectors. Failure to carefully and fully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
4. This step checks for a short to ground on the EBTCM side of the fuse. Check both fuse block terminals to verify. The fuse terminals are not identified.
7. This step checks if the fuse opens when the ignition switch is turned to the RUN position, and the ABS/TCS performs the self test during the test drive.
8. This step determines if a short to ground in the pump is causing the open fuse. If the pump checks OK, the short is in the EBTCM.
11. If the pump is running constantly in this step, the pump relay contacts are stuck closed.