Ignition System: Testing and Inspection

ELECTRONIC IGNITION (EI) SYSTEM DIAGNOSIS

DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
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:
- The ignition 1 voltage
- The IC 1 and 4 control
- The IC 2 and 3 control

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the harness connector of the ignition coil.

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.

2. Connect a test lamp between the ignition 1 voltage circuit of the ignition coil and the negative terminal of the battery.

IMPORTANT: The test lamp is used to load the circuit and may not illuminate.

3. Ignition ON, test for less than 0.1 volt between the ignition 1 voltage circuit of the ignition coil and the positive terminal of battery.
- If greater than 0.1 volt, repair the ignition 1 voltage circuit of the ignition coil for a short to ground or an open/high resistance.
4. Ignition OFF, connect a DMM between the ignition 1 voltage circuit of the ignition coil from the fuse to the harness connector terminal of the ignition coil.
- If more than 2 ohms, repair the high resistance on the ignition 1 voltage circuit.
5. If all circuits/connections test normal, replace the ignition coil.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Ignition Coil(s) Replacement