Primary Circuit Testing
- Check for correct voltage at battery terminal connector at distributor cap. Voltage should equal battery voltage in "RUN" and "START" positions.
- To test ignition coil, remove distributor cap and wires as an assembly. Connect one ohmmeter lead to "Tach" terminal and other lead to "Bat" terminal. See Fig 2.
Courtesy of GENERAL MOTORS COMPANY
Courtesy of GENERAL MOTORS COMPANY
- Reading should be 0.4-1.0 ohm. Remove ohmmeter lead from "Bat" terminal and connect to ground terminal. Reading should be infinity. If either reading is not correct, replace coil.
- Connect one ohmmeter lead to "Tach" terminal and other lead to secondary contact. See Fig 3. Reading should be infinity. If reading is not correct, replace coil.
- Disconnect pole piece leads from control module. Connect ohmmeter leads the pole piece leads. See Fig 4. Reading should be 500-1500 ohms. If not correct, replace pole piece.
- To check for pole piece ground, remove either lead from step 5
) and connect to a good ground. Reading should be infinity. If reading is not correct, replace pole piece.
- Disconnect the Radio Frequency Interference (RFI) capacitor. Connect one ohmmeter lead to capacitor terminal and other lead to ground. See Fig 5. Ohmmeter should move slightly, then return to infinity. Any continuous reading other than infinity indicates a bad RFI capacitor.
- If system is still not operating properly, and all electrical connections and wiring have been checked, replace ignition control module.
Courtesy of GENERAL MOTORS COMPANY
Courtesy of GENERAL MOTORS COMPANY
Courtesy of GENERAL MOTORS COMPANY