Testing Internally Mounted Ignition Coils

1. Disconnect the negative battery cable.

2. Disconnect the tach, ignition coil and battery primary wire connectors from the distribution cap.

3. Remove the ignition wire set retainer ring from the distributor cap.

4. Turn the hold-down fasteners counterclockwise one quarter of a turn and lift the distributor cap off the distributor.

5. Remove the coil cover from the distributor cap. This will allow you to inspect the coil and wires for damage. Replace the coil if any damage is found.

6. In the proper service manual, locate the test specifications for your vehicle's coil.

7. Turn the distributor cap over so the leads are visible. Connect the ohmmeter to the primary leads (Figure 3). The primary lead wires will be red and yellow or red and white.

8. Turn the meter to the 0-20M ohm scale. Compare your reading to the primary winding specification for your coil.

9. Remove the meter leads from the primary wires. Connect the meter from the black ground connection to the center carbon button found inside the cap. The black ground connection will be the center lead on the distributor cap.

10. Record and compare the reading to the secondary winding specification for the coil.

11. If the primary and secondary winding readings do not fall with in range indicated in the service manual, replace the coil.

12. If the coil tests within specifications, refer to the proper service manual for further diagnosis.