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.

### DTC Descriptors

DTC P1230: Fuel Pump Relay Control Circuit Low Voltage
DTC P1231: Fuel Pump Relay Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Battery Voltage - Relay Switch | 1 | 2 | -- | --
Ignition 1 Voltage - Relay Coil | P1230 | P1230 | -- | --
Fuel Pump Supply Voltage | 1 | 2 | 3 | --
Fuel Pump Relay Control | P1230 | P1230 | P1231 | --
Fuel Pump 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

The engine control module (ECM) provides a ground to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the ECM energizes 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 de-energizes the fuel pump relay after about 3 seconds.

### Conditions for Running the DTC

• | The ignition is ON or the engine is operating.

• | The DTCs runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### DTC P1230

The ECM detects the fuel pump relay control circuit is open or shorted to ground.

#### DTC P1231

The ECM detects the fuel pump relay control circuit is shorted to voltage.

### Action Taken When the DTC Sets

DTCs P1230 and P1231 are Type C DTCs.

### Conditions for Clearing the DTC

DTCs P1230 and P1231 are Type C DTCs.

### 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

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

With the ignition ON, command the fuel pump relay ON with a scan tool. You should hear an audible click for about 3-5 seconds.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the fuel pump relay.
2. Ignition ON, load test for battery voltage between the ignition 1 voltage circuit of the fuel pump relay and ground.

⇒ | If less than B+, repair the ignition 1 voltage circuit of the fuel pump relay for a short to ground or an open/high resistance.

3. With the ignition OFF, connect a test lamp between the control circuit and the ignition 1 voltage circuit of the fuel pump relay.
4. With the ignition ON, use a scan tool to command the fuel pump relay ON. The test lamp should turn ON for about 3-5 seconds and then turn OFF.

⇒ | If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.

⇒ | If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.

5. If all circuits/connections test normal, test or replace the fuel pump relay.

### Component Testing

1. Measure for 70-110 ohms of resistance 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. 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 20-amp fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay.

⇒ | 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.

• | Relay Replacement

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