Cruise Control Diagnostic System Check
WARNING: This page is about a different car, the 2001 GMC Safari and 2001 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Presence of DTCs which begin with "U" indicate some other module on class 2 serial data line is not communicating.
- Connect scan tool to Data Link Connector (DLC). DLC is located under left side of instrument panel. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST E: SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS.
- Turn ignition switch to RUN position. Attempt to establish communication Powertrain Control Module (PCM) and Electronic Brake Control Module (EBCM) on class 2 serial data circuit. If scan tool communicates with either module, go to next step. If scan tool does not communicate with either module, go to TEST D: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
- Using scan tool, select DISPLAY DTCS function. Retrieve and record any EBCM or PCM DTCs and their status. If scan tool displays any DTCs beginning with a "P" see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If scan tool displays any DTCs related ABS see appropriate SELF DIAGNOSTICS article in BRAKES.
- If scan tool does not display any DTCs, repair cruise control system by symptom. See appropriate CRUISE CONTROL SYSTEMS article.