Ignition 1 voltage is supplied to the ignition coil. The engine control module (ECM) provides a ground for the ignition coil (IC) 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.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Engine Control Module Scan Tool Information

Important: Do not perform this diagnostic procedure if you were not sent here from the misfire diagnosis or the Engine Cranks but Does Not Run diagnostic.

1. Ignition OFF, disconnect the harness connector at the ignition coil.
2. Test for less than 5 ohms between the ground circuit terminal A and ground.

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

3. Test for less than 5 ohms between the low reference circuit terminal B 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 ECM.

4. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal D and ground.

⇒	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

Important: Set the DMM to the AC Hertz scale for this test.

5. Connect a DMM between the ignition control circuit terminal C and ground.
6. Engine cranking, test for greater than 3 hertz between the appropriate ignition control circuit and ground.

⇒	If less than the specified range, test the ignition control circuit for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

7. If all circuits test normal, replace the ignition coil.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.