Distributor Cap & Coil Testing
- Remove distributor cap and coil assembly by removing wire harness connector, battery lead cap-to-housing latches. Inspect rotor, cap and coil assembly for arc-over. Replace parts as required.
- To test coil primary resistance, connect one ohmmeter lead to battery terminal on distributor cap (positive terminal external coils). See Fig. 3.
Connect other lead to tach terminal of distributor cap (negative terminal on external coils). Ohmmeter reading should be 0.4-1.0 ohms. If not within specifications, replace coil.
- To test coil secondary resistance, connect one ohmmeter lead to coil secondary contact (cap button on internal coils). See Fig. 3.
Connect other lead to tach terminal. Ohmmeter reading should be infinity on integral coils and 6, 000-30, 000 ohms on external coils.
Courtesy of GENERAL MOTORS COMPANY
- Move ohmmeter lead from tach terminal and attach to ground terminal. Ohmmeter reading should be 6, 000-30, 000 ohms on integral coils and infinity on external coils. If these tests are not to specifications, replace coil.