Electronic Ignition (EI) System Diagnosis
Electronic Ignition (EI) System Diagnosis
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Circuit/System Description
There are 3 dual-tower ignition coils that are part of the ignition control module (ICM). The ICM contains coil driver circuits that command the coils to operate. The ICM has the following circuits:
* An ignition voltage circuit
* A ground
* An ignition control (IC) 1 control circuit for the 1-4 ignition coil
* An IC 2 control circuit for the 2-5 ignition coil
* An IC 3 control circuit for the 3-6 ignition coil
* A low reference circuit
The engine control module (ECM) controls each dual-tower ignition coil by transmitting timing pulses on the ignition coil control circuit to the ICM for the proper coil to enable a spark event.
Diagnostic Aids
Inspect the spark plug wires for proper orientation.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
* J 26792 Spark Tester
* J 43244 Relay Puller Pliers
Circuit/System Testing
1. With the ignition OFF, remove the fuel pump relay using the J 43244.
2. Crank the engine and test for a spark on each cylinder spark plug wire using the J 26792. Ground the companion cylinder spark plug wire of each cylinder when it is tested.
• If a bright blue spark is present on all 6 of the cylinders, remove and inspect all of the spark plugs for proper torque, proper gap, wear, damage, and fouling. Refer to Spark Plug Replacement (Service and Repair) and Spark Plug Inspection (Testing and Inspection). Replace the spark plugs if necessary.
• If there is no spark on any of the cylinders, test the ignition voltage circuit of the ICM for an open/high resistance or short to ground, or test the ground circuit of the ICM for an open/high resistance, or a faulty ICM.
The wire circuit resistance should measure less than 3 ohms.
• If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance, refer to Spark Plug Wire Inspection (Testing and Inspection) or a faulty ICM.
• If all tests are normal, then the system is operating correctly.
Component Testing
* With positive polarity to the low reference terminal, measure for 9,000-11,000 ohms at 20-23°C (68-74°F) room temperature between each of the ignition coil control terminals and the low reference terminal of the ICM.
• If the resistance is not within the specified range, replace the ICM.
* Measure for 7,000-15,000 ohms at 20-23°C (68-74°F) room temperature between each pair of coil towers on the ICM.
• If the resistance is not within the specified range, replace the ICM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Spark Plug Wire Replacement (Service and Repair)
* Spark Plug Replacement (Service and Repair)
* Ignition Coil Replacement (Service and Repair)