Diagnosis & Repair
- Test drive vehicle and check operation of speedometer. If speedometer is not functioning correctly, see appropriate INSTRUMENT PANEL article under ACCESSORIES/SAFETY EQUIPMENT section. If speedometer is functioning correctly, go to next step.
- Access ECM behind glove box. Ensure ignition is off. Ensure shift lever is in Neutral. Lift and support front of vehicle. Turn ignition on.
- Using DVOM, backprobe ECM connector. Measure voltage between ground and terminal No. 11 (Yellow wire) at ECM E8 connector while slowly rotating front wheel. See Figure. DVOM should indicate a pulse voltage from zero to 4.5-5.5 volts.
- If voltage is as specified, replace ECM. If voltage is not as specified, check for open circuit in wiring harness between instrument cluster and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.