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
--- | --- | --- | --- | ---
Battery Voltage - Relay Switch Side | ¹ | ² | -- | --
Fuel Pump Supply Voltage | ¹ | ² | ³ | --
Fuel Pump Relay Control | P0230 | P0230 | P0230 | --
Fuel Pump Relay Ground | P0230 | P0230 | P0230 | --
Fuel Pump Ground | -- | ² | -- | --
¹Open Fuel Pump Fuse, Engine cranks but does not run ²Engine cranks but does not run ³Fuel pump operates continuously, then discharged battery

### Circuit/System Description

The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

### 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

• | Engine Control Module Replacement

• | Engine Controls Connector End Views

• | Electrical Center Identification 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

• | Engine Control Module Scan Tool Information

#### Special Tools

J 43244 Relay Puller Pliers

### Circuit/System Verification

With the ignition ON, engine OFF, command the fuel pump relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click and the fuel pump should turn ON and OFF with each command.

⇒ | If the fuel pump operates continuously, test for a faulty relay or a short to voltage in the supply voltage circuit of the fuel pump.

### Circuit/System Testing

1. With the ignition OFF, remove the fuel pump relay from the rear electrical center.
2. Test for less than 5 ohms between the ground circuit and ground.

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

3. Connect a test lamp between the fuel pump relay control circuit and the ground circuit. Command the fuel pump relay ON and OFF with a scan tool. The test lam should turn ON and OFF when changing between the commanded states.

⇒ | If the circuit test normal, replace the ECM.

4. Inspect the fuel pump fuse.

⇒ | If the fuel pump fuse is open, test for the following conditions:

• | A short to ground in the relay switch B+ circuit

• | A short to ground in the supply voltage circuit of the fuel pump

⇒ | If the circuit test normal, replace the ECM.

5. Verify that a test light illuminates between the B+ circuit and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

6. Connect a 15-amp fused jumper wire between the B+ circuit and the supply voltage circuit of the fuel pump. Verify that the fuel pump is activated.

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

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

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

⇒ | If the above circuits test normal, replace the fuel Sensor.

7. If all circuits test normal, test or replace the fuel pump relay.

### Component Testing

1. Measure for 70-100 ohms between terminals 85 and 86 of the fuel pump relay.

⇒ | If the above circuits test normal, replace the fuel sensor.

2. Measure 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 15-amp fused jumper wire between the battery positive terminal and the relay terminal 5. Connect a jumper wire between the battery negative terminal and relay terminal 86. Test for less than 2 ohms between terminals 30 and 87.

⇒ | If the resistance measures more than 2 ohms, replace the fuel pump relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

• | Primary Fuel Tank Module Replacement