Shift Light (Manual Transmission)
- These tests assume a shift light problem exists. Use this procedure only if the light will not illuminate, or illuminates all the time.
- Turn ignition on, with engine off. Note shift light. Shift light should not be on. If light is on, check for a short to ground between the bulb and ECM, or a bad ECM.
- With ignition on and engine off, ground "test" terminal of ALDL connector. SERVICE ENGINE SOON light should start to flash and shift light should come on. If light comes on, go to next step. If SERVICE ENGINE SOON light does not flash, perform DIAGNOSTIC CIRCUIT CHECK as described in BASIC TESTING
article.
- If shift light does not come on, ground Tan/Black wire at ECM terminal B7 using a jumper wire. If light still does not come on, check for blown GAUGES fuse, blown bulb or open circuit between fuse and ECM. If light came on when grounding terminal B7 with a jumper wire, problem is a bad ECM connection or bad ECM.
Courtesy of GENERAL MOTORS CORP.