P2638-TORQUE MANAGEMENT FEEDBACK SIGNAL PERFORMANCE

For a complete wiring diagram Refer to Section 8W

Theory of Operation


The Transmission Control Module (TCM) requests torque reductions over the CAN bus during a transmission shift to improve shift quality. The TCM verifies that the PCM / ECM has performed the requested torque reduction by monitoring the response to the request. If the response is not within a specified tolerance, the TCM increments a counter, and if this counter reaches a threshold, the DTC sets.


  • When Monitored:

    Engine intervention active for at least 20 ms, no engine torque errors, engine torque demand is greater than 0.

  • Set Condition:

    Torque Reduction acknowledge bit - not set, no shift aborts, the error flag Torque Reduction Acknowledge is not set, Powertrain controller not supporting torque requests.


Possible Causes
  
CAN BUS CIRCUIT DTC PRESENT
  
TRANSMISSION CONTROL MODULE
  
POWERTRAIN / ENGINE CONTROL MODULE
  

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)



Diagnostic Test

1.CHECK FOR ENGINE DTC PRESENT



Are there any engine DTCs present?

Yes


No
  • Go To 2

2.CHECK FOR CAN BUS DTCS



Are there any CAN bus DTCs present in any module other than the TCM or an overall indication of a CAN bus communication problem?

Yes


No
  • Go To 3

3.CHECK IF DTC RESETS




NOTE: If the TCM detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set and is located in scan tool under Environmental Data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set.





Did the DTC P2638-TORQUE MANAGEMENT FEEDBACK SIGNAL PERFORMANCE reset?

Yes


No