Test Description

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

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: This step determines if the PCM/TCM is transmitting class 2 serial data to the DLC and that the Class 2 data circuit is not open or shorted.
3: This step determines if an antilock brake system (ABS) DTC has disabled the all-wheel drive (AWD) system.

Diagnostic System Check - Locking/Limited Slip Rear Axle

Step	Action	Yes	No
1	Install a scan tool. 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. 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 following control modules: Electronic brake control module (EBCM) Powertrain control module (PCM) for 3.4L Transmission control module (TCM) for 3.6L Does the scan tool communicate with all control modules listed?	Go to Step 3	Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
3	Select the display DTCs function on the scan tool for the following control modules: EBCM PCM for 3.4L TCM for 3.6L Does the scan tool display any DTCs?	Go to Step 4	Go to Symptoms - Locking/Limited Slip Rear Axle
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 Step 5
5	Does the scan tool display any DTCs that begin with a "C"?	Go to Diagnostic Trouble Code (DTC) List in Antilock Brakes System	Go to Diagnostic System Check - Engine Controls in Engine Controls-3.4L or Diagnostic System Check - Engine Controls in Engine Controls-3.6L.