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. Remove ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. Reconnect ECM harness connectors. Start engine and allow it to idle. While engine is running, backprobe and measure voltage between ground and ECM harness connector G04 terminal No. 31 (Green/Yellow wire). See Figure. Voltage should pulsate between 0-1.5 volts and 10-14 volts. If voltage is not as specified, go to next step. If voltage is as specified, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If no intermittent problem is found, substitute ECM or TCM with a known good unit and repeat DTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Disconnect TCM harness connector G07. Also disconnect ECM harness connector G04. For component location, see Figure. Measure resistance between ground and TCM harness connector G07 terminal No. 27 (Green/Yellow wire). See Fig 1. If resistance is infinity, go to next step, If any resistance is found, repair short to ground in Green/Yellow wire between TCM and ECM. After repair, repeat DTC CONFIRMATION TEST .
- Turn ignition switch to ON position. Measure voltage between ground and TCM harness connector G07 terminal No. 31 (Green/Yellow wire). See Fig 1. If voltage is zero volt, go to next step, If any voltage is found, repair short to voltage in Green/Yellow wire between TCM and ECM. After repair, repeat DTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Measure resistance between ECM harness connector G04 terminal No. 31 and TCM harness connector G07 terminal No. 27 (Green/Yellow wire). See Figure and Fig 1 . If resistance is less than 3 ohms, go to next step. If resistance is 3 ohms or more, repair open or short circuit in Green/Yellow wire between TCM and ECM. After repair, repeat DTC CONFIRMATION TEST .
- Reconnect ECM harness connector G04. Turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector G04 terminal No. 31 (Green/Yellow wire). See Figure. Voltage should pulsate between 0-1.5 volts and 10-14 volts. If voltage is as specified, substitute TCM with a known good unit and repeat DTC CONFIRMATION TEST . If voltage is as not specified, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .