GM Cutlass RWD 1970-1987 Repair Guide

Ignition Coil



See Figure 1

  1. Remove the distributor cap from the housing assembly. For details, please refer to Engine Electrical of this information.
  3. Connect an ohmmeter across the primary connections, as shown by the ohmmeter and wiring on the left side (#1) of the illustration. The resistance should be zero or very close to zero. High resistance or infinite resistance indicates a partial or complete open circuit, and the need to replace the coil.
  5. Connect the ohmmeter between the primary ground and the coil secondary connector. Set the resistance to the higher scale. Test resistance as shown by the solid wire connections and then repeat the test with the wire connected as shown by the dotted line. If both readings are infinite, the coil is bad. If both or either show continuity, the coil is okay.

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Fig. Fig. 1: Testing the ignition coil - distributor cap mounted coil assemblies

Separately Mounted Coil

See Figure 2

  1. Disconnect the secondary lead and unplug the primary leads. Remove the mounting bolts and remove the coil from the engine.
  3. First connect an ohmmeter, set to the high scale, as shown on the left (#1) in the illustration. The resistance should be nearly infinite. If it is not, replace the coil.
  5. Connect the ohmmeter as shown in the center picture. Use the low resistance scale. The reading should be very low, nearly zero. Otherwise, replace the coil.

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Fig. Fig. 2: Testing the ignition coil - separately (external) mounted coil

  1. Reset the ohmmeter to the high resistance scale and connect it as shown on the right. There should be obvious continuity; the ohmmeter should not read infinite. If it does replace the coil. If all three tests are passed, the coil is satisfactory.


  1. Mark the spark plug wires. Then, carefully disconnect each from the distributor cap. Squeeze the latches together and then disengage the connector that runs from the cap to the distributor base.
  3. Use a large, flat bladed prybar to first depress and then rotate the wire type latch away from the underside of the distributor on either side. Remove the cap.
  5. Turn the cap upside down. Remove the four bolts from the four corners of the coil, noting the location of the secondary ground lead. Then, remove the primary wiring from the connector in the cap, noting the routing of positive and negative leads.
  7. Remove the coil and wiring. Then, remove the arc seal from underneath.
  9. Wipe the mounting area for the coil clean with a soft cloth. Inspect the cap for defects, especially heat or carbon tracks, and replace it if necessary.
  11. Install a new coil into position, and carefully route the primary wiring positive and negative leads properly.
  13. Position the coil ground wire as it was at removal and then install and snug up the four coil mounting bolts. Install the cap and wiring in reverse order.