P1DF8

P1DF8-ACTUAL DECREASE OF ENGINE TORQUE - HIGH

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the diagnostic is to monitor if the Powertrain Control Module (PCM) executed the torque requested by the Transmission Control Module (TCM). This is determined by comparing the PCM's executed torque to the original torque requested by the TCM over the CAN BUS. These torque requests only occur during shift operations. This diagnostic checks for engine torque reduction to high.

- When Monitored:
Ignition on with no failure in CAN BUS monitoring and no failure in CAN message monitoring.

- Set Condition:
The failure is detected if the following conditions occurs. Executed engine torque reduction is higher than the requested engine torque reduction by a calibrated amount.





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 if the fault is present.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 2

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

Are any PCM 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.