P1793

CODE NUMBER
Scan tool: 48
General scan tool: P1793

CODE NAME
TRD link communication error

CODE DESCRIPTION
Technical Description
During high torque shifts the Transmission Control Module (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 Powertrain Control Module (PCM) across the Torque Management Request Sense Circuit. The PCM will acknowledge the TCM's request by sending a message across the CCD bus within a specific amount of time. 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.

Check Area
Whenever the engine is running.

Set Conditions
This code is set when the TCM sends multiple torque reduction messages to the PCM and the TCM does not receive a response from the PCM. This code is set when less than 3 volts are present at the relay output (switched battery) terminals at the Transmission Control Module (TCM) when the TCM is energizing the relay.

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.

PROBABLE CAUSE
- Sticky Throttle Position Sensor (TPS)
- Wiring or Connector problems in the Torque Management Request Sense Circuit
- Defective PCM
- Defective TCM





DIAGNOSTIC CHART