Diagnosis & Repair Procedure
NOTE:
For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS
article in ELECTRICAL.
NOTE:
Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
- If engine system check has been performed, go to next step. If engine system check has not been performed, perform A-4: ENGINE SYSTEM CHECK under SYSTEM TESTS, then go to next step.
- Turn ignition switch to LOCK position. Locate ECM 26-pin harness connector C51-3 under instrument panel, behind glove box. See Figure . Disconnect and check ECM and harness connector C51-3 for poor, loose, corroded or damaged connector terminals. If connector terminals are faulty, repair as necessary and repeat DTC CONFIRMATION TEST . If connector terminals are okay, reconnect ECM harness connector. Start engine and allow it to idle. Backprobe and measure voltage between ground and ECM harness connector C51-3 terminal No. 3 (Black wire). See Fig 1 . If voltage is not 0.9-3.98 volts, go to next step. If voltage is 0.9-3.98 volts, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. After repair, repeat DTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Disconnect Knock sensor single pin harness connector C70, located on center of cylinder block, see Figure . Turn ignition switch to ON position. Measure voltage between ground and Knock sensor single wire harness connector C70 (Black wire). See Fig 1 . If voltage is 4-5 volts, replace faulty Knock sensor. See KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST . If voltage is not 4-5 volts, check for open or short circuit in Black wire between ECM and Knock sensor. If short is found, repair as necessary and repeat DTC CONFIRMATION TEST . If open or short circuit is not found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .