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 provide an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Fuel Pump Relay Ignition Voltage | 1 | 2 | -- | --
Fuel Pump Motor Supply Voltage | 1 | 2 | 3 | --
Fuel Pump Relay Control | P0230 2 | P0230 2 | 3 | --
Fuel Pump Relay Ground | -- | P0230 2 | -- | --
Fuel Pump Motor Ground | -- | 2 | -- | --

1. The fuel pump fuse opens and the engine cranks but does not run.
2. The engine cranks but does not run.
3. The fuel pump operates continuously and the battery will discharge.

### Circuit/System Description

When you turn ON the ignition switch, the engine control module (ECM) energizes the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the ECM receives ignition reference pulses. If there are no ignition reference pulses, the ECM shuts the fuel pump OFF within 3 seconds after the ignition was switched to the ON position or if the engine stops.

### 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

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 43244 Relay Puller Pliers

### Circuit/System Verification

Ignition ON, command the fuel pump relay ON and OFF with a scan tool. You should hear and feel a click when you command the fuel pump relay ON and OFF.

### Circuit/System Testing

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

⇒ | If the fuel pump runs continuously, test the relay switch supply circuit terminal 87 for a short to voltage. If the circuit tests normal, replace the fuel pump relay.

2. Ignition OFF, remove the fuel pump relay from the electrical center with the J 43244 .
3. Verify a test lamp illuminates between the relay ground circuit terminal 85 and B+.

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

4. Ignition ON, test for 2-3 V between the control circuit terminal 86 and ground.

⇒ | If less than the specified range, test the control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

5. Command the fuel pump ON with a scan tool. The DMM should transition from 2-3 V when commanded OFF to greater than 10 V when commanded ON.

⇒ | If the circuit voltage does not correspond to the specified values, replace the ECM.

6. Verify a test lamp illuminates between the relay switch B+ voltage circuit terminal 30 and ground.

⇒ | If the test lamp does not illuminate, repair the relay switch B+ voltage circuit for a short to ground or an open/high resistance.

7. Install a 15 A fused jumper wire between the relay switch B+ voltage circuit terminal 30 and the relay switch supply circuit terminal 87. The fuel pump should turn ON.

⇒ | If the fuel pump does not turn ON, test the relay switch supply circuit and the fuel pump motor ground circuit for an open/high resistance. If the circuits test normal, replace the fuel pump.

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

### Component Testing

1. Ignition OFF, remove the fuel pump relay from the electrical center with the J 43244 .
2. Test for 70-110 Ω between terminals 85 and 86.

⇒ | If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If not the specified value, replace the relay.

4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Fuel Pump Replacement

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