DTC P1793 for Holden Statesman 2005

Circuit Description

The Engine Control Module (ECM) sends wheel speed data to the Transmission Control Module (TCM). The data is sent to the TCM through a communication network called the GM Controller Area Network (GMLAN). Two circuits are used to communicate GMLAN data between the ECM/TCM and other modules. A fault in the GMLAN will not cause DTC P1793 to set by itself. If a GMLAN fault occurs, other DTCs will set before DTC P1793.

When the TCM receives a invalid wheel speed data from the ECM, then DTC P1793 will set, which is a type 'C' DTC.

Conditions for Running the DTC

•	Ignition voltage is between 8.0 and 18.0 volts.

•	Engine is running between 450 and 6,800 RPM for at least 5 seconds.

•	No other GMLAN errors are present.

Conditions for Setting the DTC

The TCM receives no valid wheel speed data from the ECM for 2 seconds.

Action Taken When the DTC Sets

•	The TCM records the operating conditions when the 'Conditions for Setting the DTC' have been met. The TCM stores this information as a failure record.

•	The TCM does not request the Powertrain Interface Module (PIM) to illuminate the Check Powertrain Malfunction Indicator Lamp (MIL).

•	The TCM stores DTC P1793 into TCM history.

Conditions for Clearing the MIL/DTC

•	Tech 2 can clear the DTC.

•	The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring.

•	The TCM cancels the default actions when the ignition is off long enough to power down the TCM.

Step

Action

Values

Yes

Schematic Reference: Automatic Transmission Controls Schematics

For information on testing wiring faults, refer to Wiring Systems.

Has the Diagnostic System Check - Automatic Transmission been completed?

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

Connect Tech 2 to the DLC.
Ignition ON, engine OFF.
Record any ECM DTCs.

Did you record any ECM DTCs?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

Clear the DTC.
Turn the ignition off for at least 30 seconds.
Start engine and allow to idle.

Did DTC P1793 reset?

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections

Did any other DTCs set?

Go to the Vehicle System Diagnostics that belongs to the undiagnosed DTC

Go to Step 5

Replace TCM. Refer to Transmission Control Module Replacement.

Is the replacement complete?

Go to Step 6

Perform the following operation to verify the repair:

1.1.	Select DTC on the Tech 2.

1.2.	Select 'Clear info'.

Operate the vehicle in the Conditions for Running the DTC.

Has the test run and passed?

System OK

Go to Step 2

When all diagnosis and repairs are completed, clear all DTCs and verify correct operation.