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 engine control module (ECM) provides a voltage to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the ECM turns ON the fuel pump relay, which applies power to the fuel pump. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM turns OFF the fuel pump relay after approximately 3 seconds.

### Diagnostic Aids

The following conditions may cause the fuel pump fuse to open:

• | The fuse is faulty.

• | There is an intermittent short to ground in the supply voltage circuit of the fuel pump.

• | The fuel pump has an intermittent internal condition.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Fuel System Description

#### 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

#### Special Tools

J 43244 Relay Puller Pliers

### Circuit/System Verification

Important: Fuel pump DTCs may set when using the Fuel Pump output control.

Ignition ON, command the fuel pump relay ON with a scan tool. You should hear the fuel pump operate for 3-5 seconds and then turn OFF.

### Circuit/System Testing

1. Ignition OFF, the fuel pump should not be operating.

⇒ | If the fuel pump operates continuously, test for a short to voltage in supply voltage circuit of the fuel pump. If the circuit/connections test normal, replace the fuel pump relay.

2. Test the fuel pump fuse. The fuse should not be open.

⇒ | If the fuel pump fuse is open, test for a short to ground in the supply voltage circuit of the fuel pump. If the circuit/connections test normal, replace the fuel pump.

3. Ignition OFF, remove the fuel pump relay from the electrical center.
4. Ignition ON, test for B+ between the B+ circuit terminal 30 and ground.

⇒ | If less than the specified range, repair the voltage supply circuit for an open/high resistance.

5. Connect a 15A fused jumper wire between the B+ circuit terminal 30 and the supply voltage circuit terminal 87. The fuel pump should operate.

⇒ | If the fuel pump does not operate, test for the following conditions:

• | An open/high resistance in the supply voltage circuit of the fuel pump

• | An open/high resistance in the ground circuit of the fuel pump

⇒ | If the above circuit/connections test normal, replace the fuel pump.

6. If all circuit/connections test normal, test or replace the fuel pump relay.

### Component Testing

1. Test for 70-110 ohms between terminals 85 and 86 of the fuel pump relay.

⇒ | If the resistance is not within the specified range, replace the fuel pump relay.

2. Test for infinite resistance between the following terminals of the fuel pump relay:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If continuity is detected, replace the fuel pump relay.

3. Connect a 15A fused jumper wire between B+ and relay terminal 85. Connect a jumper wire between ground and relay terminal 86. Test for less than 2 ohms between terminals 30 and 87 of the fuel pump relay.

⇒ | If greater than the specified range, replace the fuel pump relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Primary Fuel Tank Module Replacement

• | Relay Replacement