For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Circuit/System Description

The ignition system consists of one integrated and sealed ignition coil/module assembly for the 4 cylinders. The engine control module (ECM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil to enable a spark event. When the engine is running the ECM monitors each IC circuit for improper voltage levels. The ignition coil/module assembly has the following circuits:

• | Ignition voltage

• | Ground

• | IC for each coil

### Diagnostic Aids

• | A slight to moderate resistance in the ignition voltage circuit, can cause a misfire condition or a crank/no start concern.

• | Extended engine cranking time, will foul the spark plugs with excessive fuel and cause a crank/no start condition.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information.

### Circuit/System Verification

Important: Verify that the engine is in good mechanical condition before continuing with this diagnostic.

Verify the following conditions:

• | The ignition coil/module assembly is correctly connected.

• | The proper spark plug type.

• | The proper spark plug gap and torque.

| Refer to Ignition System Specifications and Spark Plug Inspection.

### Circuit/System Testing

1. Ignition OFF for 90 seconds, disconnect the harness connector at the ignition coil/module assembly.
2. Test for less than 5 ohms between the ground circuit terminal 1 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

4. Ignition ON, verify that a test lamp does not illuminate between B+ and the affected IC circuit terminal listed below:

• | IC 1 circuit: terminal 6

• | IC 2 circuit: terminal 5

• | IC 3 circuit: terminal 4

• | IC 4 circuit: terminal 3

⇒ | If the test lamp illuminates, test the IC circuit for a short to ground. If the circuit tests normal, replace the ECM.

5. Ignition OFF for 90 seconds, disconnect the ECM.
6. Test each IC circuit for less than 5.0 ohms between the ignition coil/module assembly harness connector and the ECM harness connector:

• | IC 1 circuit: terminal 6 and ECM connector X1, terminal 1 and X1, terminal 2.

• | IC 2 circuit: terminal 5 and ECM connector X1, terminal 17 and X1, terminal 18.

• | IC 3 circuit: terminal 4 and ECM connector X1, terminal 33 and X1, terminal 34.

• | IC 4 circuit: terminal 3 and ECM connector X1, terminal 49 and X1, terminal 50.

⇒ | If greater than the specified range, test the IC circuit for an open/high resistance.

7. Ignition OFF, connect the ECM.
8. Exchange the affected ignition coil/module assembly with a known good assembly.
9. Start the engine.

⇒ | If the misfire or crank/no start is resolved, replace the ignition coil/module assembly.

⇒ | If the misfire or crank/no start concern is still present, replace the ECM.

### Repair Instructions

• | Ignition Coil Replacement

• | Control Module References for ECM replacement, setup, and programming

### Repair Verification

If the customer concern was a flashing MIL, perform the following procedure:

1. Install any components that have been removed or replaced during diagnosis.
2. Perform any adjustments, programming or setup procedures that are required when a component is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 seconds.
5. If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
6. To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420. Refer to DTC P0420.