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. The ignition coil consist of the following circuits:

Schematic Reference

Engine Controls Schematics

Description and Operation

Electronic Ignition (EI) System Description

Electrical Information Reference

Scan Tool Reference

Control Module References for 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. Ignition OFF, test for less than 2 ohms of resistance between the ignition 1 voltage circuit terminal B and the fuse.

⇒	If greater than the specified range, repair the ignition 1 voltage circuit for high resistance.

3. Ignition On, command the fuel pump relay ON with a scan tool and test for battery voltage between the ignition 1 voltage circuit terminal B 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.

4. If all circuits test normal, test or replace the ignition coil.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.