Electronic Control System Gas Plus Engines – 019-105   Ignition Control Module

Two parts compose this procedure:

• Check to see that all the inputs to the Ignition Control Module (ICM) are functioning correctly.
• Check to see that the ICM outputs are functioning correctly.

Disconnect the engine harness connector from the ICM. Turn the keyswitch to the ON position.

Measure the voltage between the switched battery positive (+) pin and the battery negative (-) pin in the connector. The voltage should be equal to the battery voltage. If the voltage is incorrect, repair or replace the engine harness or the OEM harness.

Check the ICM outputs. Turn the keyswitch to the OFF position. Disconnect the ignition coil harness connector from the ICM.

Measure the resistance between the chassis ground pins on the ICM and block ground.

The resistance must be 10 ohms or less. The resistance must be 10 ohms or less.

Measure the resistance between the ICM output to each coil and block ground.

The resistance must show an open circuit (100k ohms or more).

If the circuit is not open there is an internal short in the ICM. Replace the ICM.

Check for continuity in the wiring harness between the ICM and coils. Turn the keyswitch to the OFF position.

Disconnect the ignition coil harness connector from the ICM. Measure resistance between the ICM pin connectors and the coil connectors as shown in the wiring diagram.

The resistance must be 10 ohms or less. If the resistance is incorrect, repair or replace the wiring harness.

Disconnect the 6-pin connector from the ICM. Turn the keyswitch to the ON position.

Measure the voltage between the switched battery positive (+) pin and the battery negative (-) pin in the connector. The voltage must be equal to the battery voltage. If the voltage is incorrect, repair or replace the engine harness or the OEM harness.

Check the ICM outputs. Turn the keyswitch to the OFF position. Disconnect the 4-pin connectors from the ICM.

Measure the resistance between the spark module signal (-) pin on the ICM and ground for both the right and left connectors on the ICM.

The resistance must be 10 ohms or less. If the resistance is incorrect, replace the ICM.

Check for continuity in the wiring harness between the ICM and the coils. Turn the keyswitch to the OFF position.

Disconnect the two 4-pin connectors from the ICM. Measure resistance between the ICM pin connectors and the coil connectors as shown in the wiring diagram.

The resistance must be 10 ohms or less. If the resistance is incorrect, repair or replace the wiring harness.

Unlatch the connectors by using a small screwdriver to open the connector.

Slide the latch fully to remove the connector from the ICM.

Remove the four capscrews and ICM.

Lift the lock tabs on the three harness connectors and remove them from the ICM.

NOTE: In some applications, the ICM can not be removed without first disconnecting the ECM wiring.

Remove the four capscrews and ICM.

Install the new ICM and four capscrews.

Connect the two harness connectors.

Slide the connector lock until a click sound is heard and the slide face is flush with the connector.

Install the new ICM and four capscrews.

Connect the three harness connectors.