Test A Harleydavidson Coilpack

Test the Harley Davidson ignition coil with a multimeter.

Harley-Davidson uses a mutual induction-type coil in all its models. The coil consists of a primary winding, which receives power from the ignition circuit and is controlled by the crankshaft position sensor, and a secondary winding, which steps up the voltage in the primary windings through mutual induction, and delivers this power to the spark plugs. Insulation breakdown of the internal windings is the main cause of coil failure. Test the coil after it has been removed from the bike.

Instructions

1. Set the multimeter to test for continuity. The symbol for continuity on the meter is usually something that indicates sound. It may be a sound symbol along with an omega or a sound symbol and a diode symbol. Place a probe on each of the primary winding terminals within the electrical connector on the back of the coil. The digital meter buzzes to indicate continuity — an uninterrupted path. The dial on an analog meter moves to the maximum position to indicate continuity. If the meter fails to indicate continuity — the meter does not buzz or the dial does not move — the coil is bad.

2. Place a probe on each of the secondary winding terminals within the spark plug wire towers on the coil. You should have continuity. If the meter fails to indicate continuity, the coil is bad.

3. Place a probe on one of the secondary winding terminals, and the other probe on one of the primary winding terminals. You should not have continuity. If the meter indicates continuity — the meter buzzes or the dial moves to maximum — the coil is bad.

4. Set the multimeter to test for ohms in the 10-ohm range. The symbol for ohms on the meter is indicated by the omega symbol. Place a probe on each of the primary winding terminals within the electrical connector on the back of the coil. The meter should read 0.5 to 0.7 ohms.

5. Set the multimeter to test for ohms in the 1,000-ohm range. Place a probe on each of the secondary winding terminals within the spark plug wire towers on the coil. The meter should read 5,500 to 7,500 ohms.

6. Replace the coil if it fails any of these tests. Failure indicates insulation breakdown within the coil or a break in one or both of the windings. The coil is a sealed unit and it cannot be repaired, only replaced.