P1793 (48) - Torque Reduction (TRD) Link Communication Error

Name of Code:
P1793 (48) - Torque Reduction (TRD) Link Communication Error

When Monitored:
During torque managed shifts (Throttle angle above 54 degrees). This system is also tested whenever the vehicle is stopped and the engine speed is below 1000 RPM.

Set Condition:
This code is set when the Transmission Control Module (TCM) sends two subsequent torque reduction messages to the Powertrain Control Module (PCM) via the TRD link circuit and does not receive a confirmation from the PCM over the communication bus.

Theory of Operation:
During high torque shifts the TCM will send a message requesting that the PCM reduce engine power until the shift is completed. This message is sent from the TCM to the PCM across the Torque Management Request Sense Circuit. The PCM will acknowledge the TCM's request by sending a confirmation message across the communication bus. The TRD Link communication is also tested periodically for operation whenever the engine is running and the vehicle is not moving with zero degrees throttle.

Transmission Effects:
Maximum throttle angle used by TCM will be 54 degrees. As a result a customer may complain about loss of performance or of short shifting when driving aggressively

Possible Causes:
- Sticky Throttle Position Sensor (TPS)
- Wiring or Connector problems in the Torque Management Request Sense Circuit
- Bus communication problems.
- PCM
- TCM