GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Montana 🢒 Driveline/Axle 🢒 Rear Axle Controls 🢒 Diagnostic System Check - Rear Axle Controls

Circuit Description

The Diagnostic System Check is an organized approach to identify a condition created by the rear axle controls. The Diagnostic System Check is the starting point for a rear axle controls complaint. The Diagnostic System Check directs you to the next logical step for diagnosing a rear axle control concern. Perform this check only if there is a driveability complaint or if you have been directed here from another service information section.

Follow the table to help reduce diagnostic time and help prevent unnecessary replacement of parts.

Diagnostic Aids

Important: 

   • Do not clear the DTC unless directed by a diagnostic procedure. Clearing the DTCs will erase all Freeze Frame and Failure Records stored in PCM memory.
   • Poor engine performance can sometimes be diagnosed as a rear axle driveability condition. In order to avoid mis-diagnosis of the rear axle, always perform Diagnostic System Check - Engine Controls in Engine Controls-3.4L.
   • Use a scan tool that is known to function correctly. If necessary, test the scan tool on another vehicle.
   • Ensure the scan tool contains the most current file available.
   • The scan tool will display a loss of communication error message under the following conditions:
      - The PCM power is interrupted.
      - The ignition switch is turned OFF.
      - The battery voltage level is very low.
      - A poor connection at the diagnostic link connector (DLC).

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the scan tool is receiving power through the DLC connector.

    2.

  2. This step determines if the PCM is transmitting class 2 serial data to the DLC and that the Class 2 data circuit is not open or shorted.

    3.

  3. The presence of DTCs indicates that the powertrain control module has detected a fault. Go to symptoms for other concerns.

    4.

  4. This step determines if a DTC is current or stored in history.

Step

Action

Yes

No

1

  1. Install a scan tool.

    2. Important: 

       • Check for applicable service bulletins before proceeding with this test. Perform this test only if there is a driveability complaint or if you have been directed to this table from another section in the service information.
       • Do not turn the ignition OFF when performing this diagnostic procedure. Do not clear the DTCs unless instructed by this diagnostic procedure.

  2. Turn ON the ignition, with the engine OFF.

Does the scan tool turn ON?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

Attempt to establish communication with the PCM.

Does the scan tool communicate with the PCM?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the powertrain control module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms - Rear Axle Controls

4

Does the scan tool display any DTCs which begin with a "U"?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Diagnostic System Check - Engine Controls in Engine Controls-3.4L.