Ignition System Tests
- Before testing ignition system, be sure battery is fully charged and in good condition. Make sure that starter and fuel systems are operating properly. Ensure that engine is in good mechanical condition.
- Make sure that all electrical connections are clean and tight. Due to high voltage, use care when working on electronic ignition system. Connect or disconnect ignition system wiring ONLY with ignition off.
- Connect voltmeter positive lead to terminal 5 of diagnostic connector and negative lead to ground. See Fig 1. Turn ignition on. Voltmeter should indicate battery voltage. If reading is incorrect, test voltage supply through ignition switch.
- If reading is correct, test voltage between terminal 4 and 5 of diagnostic connector. Voltmeter should indicate zero volts. If reading is okay, go to step 6). If reading is 0.1 volts or more, immediately turn ignition off and go to next step.
- Replace ignition control unit. After replacing unit, test ignition coil resistance. See IGNITION COIL RESISTANCE TEST in this article. If coil resistance is okay, end test.
- Check dwell angle (at idle) at diagnostic connector or TD terminal. Dwell angle should be within specification. If dwell angle is above specification, replace ignition control unit. If dwell angle is correct or if there is no reading, go to next step.
- Disconnect pick-up coil connector (Green cable) from ignition control unit. Attach ohmmeter leads to center pin (terminal 7) and to larger, outer, circular pin (terminal 3 or 31d) of Green cable. Ohmmeter reading should be 500-700 ohms. If reading is correct, go to step 9).
- If reading is incorrect, disconnect Green cable at distributor. Connect ohmmeter between distributor terminals. If reading is now correct, replace Green cable. If resistance is still incorrect, replace distributor, then go to next step.
- With Green cable disconnected from control unit, test pick-up coil resistance between terminal 7 and ground. Also between terminal 3 and ground. Ohmmeter reading should be 200,000 ohms or greater, up to infinity. If reading is correct, end test.
- If reading is incorrect, disconnect Green cable at distributor. Connect ohmmeter between either distributor terminal and ground. Resistance reading should be 200,000 ohms or greater, up to infinity. If resistance is incorrect, replace distributor.