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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage - Fuse to Splice | ¹ | ² | -- | --
Ignition 1 Voltage - Splice to Injector | ¹ | P0201, P0202, P0203, or P0204 | -- | --
Fuel Injector 1 Control | P0201 | P0201 | P0201 | --
Fuel Injector 2 Control | P0202 | P0202 | P0202 | --
Fuel Injector 3 Control | P0203 | P0203 | P0203 | --
Fuel Injector 4 Control | P0204 | P0204 | P0204 | --
¹Open fuse, cranks no start ²Cranks no start

### Circuit/System Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

#### Special Tools Required

J 44603 Injector Test Lamp

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at a fuel injector.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 or A and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the fuel injector.

3. Ignition OFF, connect a J 44603 between the control circuit terminal 2 or B and the ignition circuit terminal 1 or A of each fuel injector one at a time.
4. Engine cranking, the test lamp should flash for each injector.

⇒ | If the test lamp is always ON, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the engine control module (ECM).

⇒ | If the test lamp is always OFF, test the appropriate control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the fuel injector. Refer to Fuel Injector Diagnosis .

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References

• | Fuel Injector Replacement