Cap & Coil Testing
- Remove cap and coil assembly by removing wiring harness connector and battery lead and by turning 4 cap-to-housing latches. Inspect rotor, cap and coil assembly for arcing. Replace cap or rotor as required.
- To test coil primary resistance, connect ohmmeter leads to battery terminal and "TACH" terminal on distributor cap. See Fig 1 .
Ohmmeter reading should be 0.4 - 1.0 ohm. Connect ohmmeter leads to "TACH" terminal and ground. Reading should be infinity. If either reading is not to specification, replace ignition coil.
- To test coil secondary resistance, connect ohmmeter leads to "TACH" terminal and coil secondary contact (cap button). Ohmmeter reading should be infinity. Move ohmmeter lead from "TACH" terminal to ground terminal on cap. Secondary-to-ground reading should be 6000-30, 000 ohms. If either reading is not within specification, replace ignition coil.
Courtesy of GENERAL MOTORS COMPANY