GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Equinox 🢒 Brakes 🢒 Park Brake 🢒 DTC P1792

Circuit Description

The powertrain control module (PCM) sends engine coolant temperature data to the transmission control module (TCM). The TCM uses this data to initiate warm-up shift patterns and to establish default transmission fluid temperature (TFT) values. The data is sent to the TCM through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the PCM and TCM. A fault in the CAN will not cause DTC P1792 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P1792.

When the TCM receives invalid engine coolant temperature data from the PCM, then DTC P1792 will set. DTC P1792 is a type C DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1792 Engine Coolant Signal

Conditions for Running the DTC
    • The ignition voltage is 10.2-15.5 volts.
    • The engine run time is 3 seconds or greater.
    • No CAN DTC U2105.
    • Trans. Protection Mode is OFF.
    • The engine speed is 400 RPM or greater.

Conditions for Setting the DTC

The PCM sends no valid engine coolant temperature data to the TCM for 4 seconds.

Action Taken When the DTC Sets
    • The TCM does not request the PCM to illuminate the malfunction indicator lamp (MIL).
    • The TCM uses 80°C (176°F) as a default engine coolant temperature value.
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
    • The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Record.
    • The TCM stores DTC P1792 in TCM history.

Conditions for Clearing the MIL/DTC
    • The PCM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
    • A scan tool can clear the MIL/DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle in Vehicle DTC Information?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.

    3. Important: 

       • Before clearing the DTC, use the scan tool in order to record the PCM and the TCM Failure Records. Using the Clear Eng./Trans. DTC Info function erases the Failure Records from the PCM and TCM.
       • Using the Clear Eng./Trans. DTC Info function erases stored DTCs in both the PCM and TCM.

  3. Record the DTC Failure Records.

Did you record any PCM Failure Records?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3
  1. Clear the DTC.
  2. Turn the ignition OFF for at least 30 seconds.
  3. Start, and allow the engine to idle.

Did DTC P1792 reset?

--

Go to Step 4

Go to Intermittent Conditions in Engine Controls - 3.4L

4

Did any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 5

5

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Is the action complete?

--

Go to Step 6

--

6

Perform the following operation to verify the repair:

  1. Select DTC on the scan tool.
  2. Select Clear Info.
  3. Start, and allow the engine to idle.
  4. Select Specific DTC.
  5. Enter DTC P1792.

Does the DTC reset?

--

Go to Step 2

Go to Step 7

7

With the scan tool, observe the stored information, capture info and DTC info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK