Test Description

WARNING: This page is about a different car, the 2004 GMC Safari and 2004 Chevrolet Astro. 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.

2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
3: The symptom list in Symptoms will determine the correct diagnostic procedure to use.

Diagnostic System Check - Cruise Control

Step	Action	Yes	No
1	Install a scan tool. Does the scan tool power up?	Go to Step 2	Go to Scan Tool Does Not Power Up in Data Link Communications
2	Turn ON the ignition, with the engine OFF. Attempt to establish communication with the Powertrain Control Module (PCM) and Electronic Brake Control Module (EBCM). Does the scan tool communicate with the control modules?	Go to Step 3	Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
3	Select the PCM display DTC function on the scan tool. Does the scan tool display any DTCs?	Go to Diagnostic Trouble Code (DTC) List in Engine Controls-4.3L	Go to Step 4
4	Select the EBCM display DTC function on the scan tool. Does the scan tool display any DTCs?	Go to Diagnostic Trouble Code (DTC) List in Antilock Brake System	Go to Symptoms - Cruise Control