Retrieving Codes
- Perform diagnostic circuit check before diagnosing vehicle using self-diagnostic system. See appropriate DIAGNOSTIC CIRCUIT CHECK chart under DIAGNOSTIC CODE CHARTS
.
- Fault code(s) can be retrieved using a scan tester connected to Data Link Connector (DLC) or by counting flashes of Malfunction Indicator Light (MIL) after grounding the diagnostic request terminal in the duty check data link connector, located near battery. See Fig 1
and Fig 2
.
- Turn ignition off. Using a jumper wire, jumper between duty check data link connector terminals No. 2 and 3. Turn ignition on and observe MIL to read fault codes. Proceed to appropriate charts under DIAGNOSTIC CODE CHARTS
to diagnose fault codes.
- If no fault codes are stored, MIL will flash Code 12, indicating ECM diagnostic system is operating. If fault codes are stored, code will flash 3 times starting with the lowest code.
Courtesy of GENERAL MOTORS CORP.
Courtesy of GENERAL MOTORS CORP.