Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor DTC P0351-P0356 and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read and record FAIL RECORDS data for DTCs P0351-P0356. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0351-P0356, go to next step. If scan tool does not display any DTC, check for an intermittent problem. See DIAGNOSTIC AIDS .
3. Check ignition control module for poor connection or damaged terminals. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
4. Check PCM harness connector for poor connection or damaged terminals. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Turn ignition on. Backprobe voltmeter between ground and affected ignition control circuit at PCM harness connector. If reading is 25-55 mV, go to next step. If reading is not 25-55 mV, go to step  8.
6. Start engine and let idle. Backprobe voltmeter between ground and ignition control circuit at PCM harness connector for cylinder being tested. If reading toggles between 100 and 180 mV, go to next step. If reading does not toggle between 100 and 180 mV, replace PCM. Retest system.
7. Turn ignition off. Disconnect 3-pin and/or 5-pin connectors at ignition control module/ignition coil. Measure voltage of affected ignition control circuit at ignition control module while cranking engine. If reading is 200-1200 mV, replace ignition control module. If reading is not 200-1200 mV, repair open in affected ignition control circuit. Retest system.
8. Turn ignition off. Disconnect PCM and ignition control module harness connectors. Using ohmmeter, check affected ignition control circuit for a short to ground, voltage, or open circuit. Repair as necessary. If circuit is okay, go to next step.
9. Turn ignition on. Using voltmeter, check affected ignition control circuit for a short to voltage. Repair as necessary. If circuit is okay, replace PCM. Retest system.