Electronic Ignition (EI) System Diagnosis

Electronic Ignition (EI) System Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

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

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 of the ignition coil.

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

2. Connect a test lamp between the ignition 1 voltage circuit of the ignition coil and ground.
3. Command the fuel pump relay ON with a scan tool and test for battery voltage between the ignition 1 voltage circuit of the ignition coil and ground.

• If less than B+, 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. Verification Tests

Ignition Coil Replacement