lemon-mirror:
Home >> GMC >> 1998 >> Envoy >> Repair and Diagnosis >> Electrical >> Gauges >> Instrument Panel >> Symptom Testing >> Speedometer Does Not Operate Properly

Speedometer Does Not Operate Properly

CAUTION: On 4WD and AWD models, ensure all wheels are supported off the ground.
  1. Perform INSTRUMENT PANEL CLUSTER (IPC) SYSTEM CHECK  under SYSTEM TESTING. Go to next step.
  2. Raise and support vehicle with wheels off the ground. Start engine and put vehicle in gear (wheels spinning). Using scan tool, check vehicle speed. If scan tool reading and expected vehicle speed are the same, go to next step. If scan tool reading and vehicle speed do not match, go to step 5).
  3. Compare scan tool reading and IPC speedometer reading. If readings are within 3 MPH, system is okay. If readings do not match, go to next step.
  4. Replace IPC. Perform INSTRUMENT PANEL CLUSTER (IPC) SYSTEM CHECK  under SYSTEM TESTING.
  5. Check for speed input (3-5 volts AC (RMS scale)) at IPC connector terminal A4 (Dark Green wire). See Figure . If input exists, PCM/VCM is sending wrong information. See appropriate TESTS W/CODES article in ENGINE PERFORMANCE section:

    If input does not exist, go to next step.

  6. Check for open or short to battery voltage in Dark Green wire between IPC and VCM/PCM. Check IPC and VCM/PCM connectors. Repair as necessary. If problem was repaired, perform INSTRUMENT PANEL CLUSTER (IPC) SYSTEM CHECK  under SYSTEM TESTING. If no problem was found, See appropriate TESTS W/CODES article in ENGINE PERFORMANCE section:
· About lemon-mirror