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

Engine Control Module Connector End Views

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 a misfire DTC 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 2 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 2 ohms between the EST return circuit terminal B and ground.

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

4. Ignition ON, load test for B+ between the ignition 1 voltage circuit terminal D and ground.

⇒	If less than the specified range, 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.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.