Ignition Control System Tests
- Check Ignition System For Proper Spark - Remove each ignition coil from each spark plug. Install a known-good spark plug to ignition coil and position spark plug so it is grounded to engine. Disconnect fuel pump relay. Crank engine. If a spark does not occur at each spark plug go to next step. If a spark does occur at each spark plug, see FUEL PUMP CIRCUIT TESTS .
- Check Power Supply Circuit Of Ignition Coil - Turn ignition off. Disconnect connector from ignition coil on faulty cylinders. Turn ignition on. Check power supply voltage between terminal No. 1 of each coil connector and engine ground. If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, repair open in harness between ignition coil and ignition switch connector or poor contact in coupling connector.
- Check Ignition Coil - Turn ignition off. Check resistance between each ignition coil connector terminals No. 1 and 2 to check primary coil. Resistance should be between .45 and 1.05 ohms. If resistance is not as specified, replace ignition coil. If resistance is within specifications, check for poor contact in ignition coil connector or spark plug contact portion. Repair as needed. If no repair is needed, disconnect connector from ignition coil on normal cylinder and remove coil. Connect normal ignition coil connector to engine harness ignition coil connector for faulty cylinder. Install new spark plug on ignition coil. Ground spark plug to engine. Crank engine. If spark occurs at faulty cylinder, replace faulty ignition coil. If no spark, go to next step.
- Check Harness Between Ignitor & Ignition Coil Connector - Turn ignition off. Disconnect 6-pin connector from ignitor. Check resistance of harness circuit between each ignition coil and ignitor connector. If resistance is less than one ohm, go to next step. If resistance is more than one ohm, check for poor contact in coupling connector or spark plug contact. Repair as needed. If repair is not needed, repair open circuit in harness between ignition coil and ignitor connector.
- Check Ignitor Harness Ground Circuit - Disconnect 7-pin connector from ignitor. Check resistance between ignitor connector terminal No. 4 and engine ground. If resistance is less than 5 ohms, go to next step. If resistance more than 5 ohms, repair open circuit in harness between ignitor connector and engine grounding terminal or poor contact in coupling connector.
- Check Harness Between ECM & Ignitor Connector
- Disconnect ECM connector. Check resistance between ECM and ignitor connector. See the ECM & IGNITOR HARNESS IDENTIFICATION
table for connector terminal identification. If resistance is not less than one ohm, repair open circuit in harness between ECM and ignitor connector. If resistance is less than one ohm, check resistance of ECM harness connector terminals No. 41, 68, 67, 66, 65, and 40 to ground. If resistance is less than one megohm, repair short circuit in harness between ECM and ignitor connector. If resistance is more than one megohm, check for poor contact in ECM connector. Repair if needed. If repair was not necessary, go to next step.ECM & IGNITOR HARNESS IDENTIFICATION
ECM Terminal No. Ignitor Terminal No. 41 7 68 6 67 5 66 3 65 2 40 1 94 4 - Check Ignitor Input Signal - Reconnect ignitor connectors. Backprobe 7-pin connector terminals to check voltage between ignitor connector terminals and ground. See IGNITOR INPUT SIGNAL TERMINAL IDENTIFICATION table. Ensure input signal voltage fluctuates with engine speed while cranking. If no voltage, replace ignitor. If voltage is 10 volts or more, go to next step.
IGNITOR INPUT SIGNAL TERMINAL IDENTIFICATION
| Terminal No. | Cylinder No. |
|---|---|
| 7 | 1 |
| 2 | 6 |
| 3 | 5 |
| 4 | 3 |
| 5 | 2 |
| 6 | 1 |