Except M42 and M50 Engines
- With the ignition OFF, disconnect the ignition lead from the coil tower. Disconnect the primary wires from the screw terminals on the coil. Note that the terminals are marked with a 1 and 15. The center tower terminal is called 4.
- Use an ohmmeter and check the resistance between the 2 screw terminals, 1 and 15. The resistance should be 0.45-0.55 ohms.
- Use an ohmmeter and check the resistance between the terminals, 4 and 15. The resistance should be 5400-6600 ohms.
- Replace the coil if not in specification.
See Figures 1, 2 and 3
- On the M50 engine, remove the valve cover cladding as done when removing spark plugs. On the M42 engine, pull off the coil pack cover.
- With the ignition OFF, disconnect the harness connector by releasing the locking bar and pulling off the connector.
- Check the resistance between the outside terminals of the the 3 terminals in the coil connector socket. They are terminals 1 and 15.
- The resistance should be 0.4-0.8 ohms. Replace the coil if out of specification. The secondary side of the coil cannot be checked due to the design of the coil.