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

Ignition 1 voltage is supplied to the ignition coils. 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.

### Diagnostic Aids

• | The ignition coils for each bank are fused separately. If a fuse opens or the ignition 1 voltage circuit opens between the fuse and the splice, all the ignition coils for one bank of the engine would be inoperative. If the ground circuit opens at the engine block, the ignition coils would be inoperative for one bank of the engine

• | Inspect the ignition coils for aftermarket devices. An aftermarket device connected to the ignition coil circuits, may cause a condition with the ignition coils.

### 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 Testing

Note: 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. Ignition ON, load 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.

3. Ignition OFF, test for less than 5 Ω of resistance between the ground circuit of the ignition coil and the negative terminal of the battery.

⇒ | If greater than 5 Ω, repair the ground circuit of the ignition coil for an open/high resistance.

4. If all circuits/connections test normal, replace the ignition coil.

### Repair Instructions

Perform the Diagnostic Repair Verification.

• | Ignition Coil Replacement - Bank 1

• | Ignition Coil Replacement - Bank 2