Measure the primary resistance by connecting an ohmmeter across the positive
(+) and negative (–) terminals of the coil. Primary resistance, at 68°F
(20°C), should be 0.90.09.
Measure the secondary resistance by connecting an ohmmeter across the center
tower connector and the positive (+) terminal. Resistance, at 68°F (20°C),
should be 6–30K.
If a megaohm tester is available, connect it between the negative (–)
terminal and the outside of the coil casing. This will test the coil insulation
and show if there is an internal short. Resistance, at 68°F (20°C),
should be>10M.
- Connect an ohmmeter set to the X1 scale to the plug and minus primary connectors
of the coil, as shown. The coil should have good continuity. That is, resistance
should be approximately 1–1.3except on the 2,654cc, on which the resistance
should be approximately 0.72–0.88.
- Disconnect the high tension wire and move the connector leading to the minus
terminal over to the metallic connector inside the coil tower. Set the ohmmeter
to the X1000 scale. Resistance must be 10,000–30,000.
- You can also check for bad coil insulation by measuring the resistance between
the coil (–) primary connection and the metal body (case) of the coil.
If resistance is less than 10m, replace the coil. This test may not be entirely
satisfactory unless you have a megaohm tester that records 500 volts. If the
tests below do not reveal the problem and, especially, if operating the engine
at night may produce some bluish sparks around the coil, you may want to remove
the coil and have it tested at a diagnostic center.
- If the coil resistances are not as specified, replace the coil.
If the coil tests out ok, replace the igniter and pickup coil. However,
you should make sure before doing this work that there are no basic maintenance
problems in the secondary circuit of the system, since it is often impossible
to return electrical parts. We suggest that before you replace the igniter
and pickup coil, you carefully inspect the cap and rotor for carbon tracks
or cracks and disconnect the wires and measure their resistance with an
ohmmeter. Resistance should be 16,000per length of 100cm. Also, check for
cracks in the insulation. Replace secondary parts as inspection/testing
deems necessary before replacing the igniter and pickup coil.
Two coils, leading and trailing, are used. The leading coil is type HP5-13J;
the trailing, type HP5-13E.
- Measure the primary resistance by connecting an ohmmeter across the positive
(+) and negative (–) terminals of the coil. Primary resistance, at 68°F
(20°C), should be 1.35on the leading coil; 1.46on the trailing coil.
- Measure the secondary resistance by connecting an ohmmeter across the center
tower connector and the positive (+) terminal. Resistance, at 68°F (20°C),
should be 8.7Kon the leading coil; 9.5Kon the trailing coil.
- Check across the external resistor on each coil. Resistance, at 68°F
(20°C), should be 1.4on the leading coil; 1.6on the trailing coil.
