Diagnosis & Repair (Using OBD-II Scan Tool)
- Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (Brown/White wire) at ECM harness connector E6. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
- Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Brown/White wire) and No. 21 (Red wire) at ECM harness connector E6. With fully closed throttle, voltage should be .3-.9 volt. With fully open throttle, voltage should be 3.2-4.8 volts. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Brown/White wire) and No. 9 (Red/Black wire) at ECM harness connector E6. With fully closed throttle, voltage should be 1.8-2.7 volts. With fully open throttle, voltage should be 4.7-5.1 volts. If voltage readings are as specified, replace ECM. If voltage readings are not as specified, go to next step.
- Check APP sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace APP sensor. If problem does not exist, repair open or short in wiring between ECM and APP sensor. See WIRING DIAGRAMS article.