Electronic Ignition (EI) System Diagnosis

Electronic Ignition (EI) System Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Strategy Based Diagnosis Strategy Based Diagnosis
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions

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

Reference Information

Schematic Reference

Engine Controls Schematics (w/Throttle Actuator Controls) Electrical DiagramsEngine Controls Schematics (w/o Throttle Actuator Control) Electrical Diagrams

Connector End View Reference
* Engine Controls Connector End Views (w/ Throttle Actuator Control) Engine Controls Connector End Views (w/ Throttle Actuator Control)Engine Controls Connector End Views (w/o Throttle Actuator Control) Engine Controls Connector End Views (w/o Throttle Actuator Control)
* Engine Control Module Connector End Views (w/ Throttle Actuator Control) Engine Control Module Connector End Views (w/ Throttle Actuator Control)Engine Control Module Connector End Views (w/o Throttle Actuator Control) Engine Control Module Connector End Views (w/o Throttle Actuator Control)

Description and Operation

Electronic Ignition (EI) System Description Electronic Ignition (EI) System Description

Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference
* Scan Tool Data List (w/ Throttle Actuator Control) Scan Tool Data List (w/ Throttle Actuator Control)Scan Tool Data List (w/o Throttle Actuator Control) Scan Tool Data List (w/o Throttle Actuator Control)
* Scan Tool Data Definitions (w/ Throttle Actuator Control) Scan Tool Data Definitions (w/ Throttle Actuator Control)Scan Tool Data Definitions (w/o Throttle Actuator Control) Scan Tool Data Definitions (w/o Throttle Actuator Control)
* Scan Tool Output Controls (w/ Throttle Actuator Control) Scan Tool Output Controls (w/ Throttle Actuator Control)Scan Tool Output Controls (w/o Throttle Actuator Control) Scan Tool Output Controls (w/o Throttle Actuator 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.
2. Connect a test lamp between the ignition 1 voltage circuit and ground.
3. Ignition ON, command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, repair the ignition 1 voltage circuit for a short to voltage.

• If the test lamp is always OFF, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance.

4. Ignition OFF, measure for less than 2 ohms of resistance between the ignition 1 voltage circuit of the ignition coil and the fuse.

• If more than the specified value, 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 Verification Tests after completing the diagnostic procedure.

Ignition Coil Replacement Service and Repair