Electrical checks of the ignition system

If you suspect a malfunction of the ignition system, first of all make sure that all its components are clean and dry, and the terminals are not oxidized and securely fastened. Check Status (charge level) batteries and the correct setting of the ignition timing.

If the engine still does not start after troubleshooting, perform the following special checks.

Models 3.0 l

1. Disconnect the BB wire from the suspect spark plug and connect it to a known good spark plug. Set the spark plug gap to approximately 6 mm, securely ground the spark plug body to ground, and have an assistant crank the engine. If no spark occurs, proceed to the checks below.

2. Remove all BB wires and use an ohmmeter to test them for a specific (with a given resistive resistance) conductivity. Check the condition of the BB wire terminals.

3. Disconnect the coil electrical connector. Turn the ignition on and check for battery voltage at terminal 1 of the harness connector (see accompanying illustration). There must be tension.



4. With the ignition off, disconnect the electrical connector of the distributor. Check for continuity in the wiring between the coil harness connector and the distributor harness connector (see accompanying illustration).




5. Disconnect the BB wire from the ignition coil. Give fixing bolts and remove the coil from the car.

6. Using an ohmmeter, measure the resistance between the terminals of the ignition coil. The required value is 0.8÷1.0 Ohm.

7. Measure the resistance between terminal 1 of the coil connector and terminal BB of the coil wire. The required value is 7.6÷11.4 kOhm.

8. If necessary, replace the coil.

9. Remove the distributor cap. Crank the motor until the signal rotor blade is aligned with the protrusion on the inductive pickup. Using a clean blade-type feeler gauge, measure the air gap between the rotor blade and the sensor lip. If necessary, loosen the fixing screws and adjust the position of the sensor accordingly.

10. If no abnormalities are found during the above checks and the engine does not start, remove the spark plugs and check their general condition and electrode gap.

Models 4.2 l

1. Disconnect the BB wire from the suspect spark plug and connect it to a known good spark plug. Set the spark plug gap to approximately 6 mm, securely ground the spark plug body to ground, and have an assistant crank the engine. If no spark occurs, proceed to the checks below.


2. With the ignition on, use a probe lamp to check for power at the positive terminal of the primary circuit of the ignition coil. If there is no power (the lamp is off), check for continuity in the wiring between the battery, the ignition switch and the coil.

3. Remove all BB wires and use an ohmmeter to test them for a specific (with a given resistive resistance) conductivity. Check the condition of the BB wire terminals.

4. Disconnect the negative wire from the battery and the wiring from the ignition coil.

5. Using an ohmmeter, measure the resistance between the positive and negative terminals of the primary circuit of the coil. The required value is 1.08÷1.32 Ohm.

6. Measure the resistance between the positive terminal of the primary circuit and the BB terminal of the ignition coil wire. If the measurement result is outside the range of 9.0÷13.4 kOhm, replace the coil.

7. If no abnormalities are found during the above checks and the engine does not start, remove the spark plugs and check their general condition and electrode gap.