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 TEST D: ENGINE SYSTEM CHECK under SYSTEM TESTS, then go to next step.
- Turn ignition switch to LOCK position. Locate ECM. See Figure. Remove ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. Check ECM and harness connectors 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 connectors and turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector C45 terminal No. 13 (Red wire). See Figure. If voltage is not 0.5-4.5 volts, go to next step. If voltage is 0.5-4.5 volts, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO-CODES article. If no intermittent problem is found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Disconnect knock sensor single pin harness connector C37. See Figure. Turn ignition switch to ON position. Measure voltage between ground and knock sensor harness connector C37 (Red wire). See Fig 1. If voltage is 4-5 volts, go to step 5. If voltage is not 4-5 volts, repair open circuit in Red wire between Knock sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Disconnect ECM harness connector C45. Measure resistance between ground and ECM harness connector C45 terminal No. 13 (Red wire). See Figure. If resistance is infinity, go to next step. If any resistance is found, check for short to ground in Red wire between Knock sensor and ECM. If no short is found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
- Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector C45 terminal No. 13 (Red wire). See Figure. If voltage is zero volt, go to next step. If any voltage is found, check for short to voltage in Red wire between knock sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
- Measure resistance between ECM harness connector C45 terminal No. 13 and knock sensor single wire harness connector C37 (Red wire). See Figure and Fig 1 . If resistance is less than 5 ohms, replace faulty knock sensor. See KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST . If resistance is 5 ohms or more, repair short circuit in Red wire between Knock sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .