Transmission Control Module (TCM) - 8HP45

P1C4E-ABS DTC PRESENT

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the diagnostic is to prevent a down shift or engaging the park pawl during a lock up of the driven wheels which is caused by a failure or disablement of the Anti-lock Brake System (ABS).

- When Monitored:
When the ignition switch is turned to the run position.

Failure of ABS functionality or disablement of ABS functionality as indicated by the ABS module.

Engaged brake switch or failure in brake signal is indicated.

- Set Condition:
The failure is detected if the delta output speed (difference between previous and current measurement) is greater than a calibrated threshold for an amount of time.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 8HP45 Pre-Diagnostic Troubleshooting Procedure

1. CHECK FOR TCM CAN BUS DTCS
1. With the scan tool, read TCM DTCs.

Are any TCM CAN BUS DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure. Perform the diagnostic procedure for DTC U0001-CAN C BUS first.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 2

2. CHECK IF ABS DTCS ARE PRESENT
1. With the scan tool, read ABS DTCs.

Are any ABS DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Using the schematics as a guide, check the Transmission Control Module A (TCMA) terminals for corrosion, damage or terminal push out. If no problems are found, replace and program the TCMA. Valve Body - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.