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Electronic Ignition System Diagnosis

Ignition voltage is supplied to the ignition coil. The engine control module (ECM) provides an ground for the ignition coil control circuits. When the ECM removes the ground path of the ignition primary coil, the magnetic field produced by the coil collapses. The collapsing magnetic field produces a voltage in the secondary coil which ignites the spark plugs. The sequencing and timing are controlled by the ECM.

If the condition is intermittent, moving the related harnesses and connectors, with the engine running, while monitoring the appropriate scan tool Misfire Current Cylinder parameter and the appropriate Ignition Coil Control Circuit Status parameter this may help to isolate the condition.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Vehicle OFF, disconnect the harness connector at the K35 ignition coil module.
2. Test for less than 5 Ω between the ground circuit terminal B and ground.

⇒	If greater than the specified range, repair the ground circuit for an open/high resistance.

3. Vehicle OFF, all systems OFF. It may take up to 2 minutes for all the systems to power down. Test for less than 5 Ω between the low reference circuit terminal C and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

4. Vehicle in Service Mode, verify that a test lamp illuminates between the ignition voltage circuit terminal A and ground.

⇒	If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

5. If all circuits test normal, test or replace the K35 ignition coil module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.