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 | * | ** | -- | --
Ignition 1 Voltage - Relay Coil | P1230 | P1230 | P0563 | --
Fuel Pump Supply Voltage | * | ** | *** | --
Fuel Pump Relay Control | P1230 | P1230 | P1231 | --
Fuel Pump Ground | -- | ** | -- | --
* The fuel pump fuse opens and the engine cranks but does not run. ** The engine cranks but does not run. *** 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 once the above conditions are met.

### Conditions for Setting the DTC

#### P1230

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

#### P1231

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

### Action Taken When the DTC Sets

DTC P1230 and P1231 are Type C DTCs.

### Conditions for Clearing the DTC

DTC P1230 and P1231 are Type C DTCs.

### Diagnostic Aids

The following table illustrates the fuel pump relay terminal location in the underhood fuse block:

ENGINE Relay Terminal Identification
B+ - Switch | FP Relay Control
Ignition 1 Voltage - Coil | FP Motor
Front of Vehicle

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component 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

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, command the Fuel Pump Relay ON with a scan tool. You should hear an audible click for about 3-5 seconds.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel pump relay.
2. Ignition ON, command the fuel pump relay ON with a scan tool. Test for battery voltage between the relay switch ignition 1 voltage circuit terminal 86 and ground.

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

3. Ignition OFF, connect a test lamp between the relay switch control circuit terminal 85 and the relay switch ignition 1 voltage circuit terminal 86.
4. Ignition ON, command the fuel pump relay ON with a scan tool. The test lamp should turn ON for about 3-5 seconds and then turn OFF.

⇒ | If the test lamp is always ON, test the relay switch control circuit for a short to ground. If the circuit tests normal, replace the ECM.

⇒ | If the test lamp is always OFF, test the relay switch 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 pump relay.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the fuel pump relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86.

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

4. Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module References for engine control module replacement, setup, and programming