Test Description

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 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) - Determine if the Powertrain Control Module (PCM) has set DTC's which may affect Engine Cooling operation are present.

4) - The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - Engine Cooling

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
2	1) Turn ON the ignition, with the engine OFF. 2) Attempt to establish communication with the Powertrain Control Module (PCM). Does the scan tool communicate with the PCM?	Go to step 3	Go to SCAN TOOL DOES NOT POWER UP
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 - Engine Cooling
4	Does the scan tool display any DTCs which begin with a "U"?	Go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DATA LINK COMMUNICATIONS	Go to Diagnostic Trouble Code (DTC) List