Diagnostic Instructions
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 about 3 seconds.
Diagnostic Aids
The following conditions may cause the fuel pump fuse to open:
| • | There is an intermittent short to ground in the supply voltage circuit of the fuel pump. |
| • | The fuel pump has an intermittent internal condition. |
| • | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault
if there is a condition with the circuit or a connection. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Description and Operation
Fuel System Description
Electrical Information Reference
Scan Tool Reference
Special Tools Required
J 43244
Relay Puller Pliers
Circuit/System Verification
- 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.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- 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. |
- 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. |
- Ignition OFF, remove the fuel pump relay from the electrical center.
- Ignition ON, test for battery voltage between the B+ voltage circuit of the fuel pump relay and ground.
| ⇒ | If less than B+, repair the B+ voltage circuit of the fuel pump relay for an open/high resistance. |
- Connect a 15-amp fused jumper wire between the B+ circuit of the fuel pump relay and the supply voltage circuit of the fuel pump. 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. |
- If all circuit/connections test normal, test or replace the fuel pump relay.
Component Testing
- Measure for 110-150 ohms of resistance between terminals 1 and 2 of the fuel pump relay.
| ⇒ | If the resistance is not within the specified range, replace the fuel pump relay. |
- Measure for infinite resistance between the following terminals of the fuel pump relay:
| ⇒ | If continuity is detected, replace the fuel pump relay. |
- Connect a 15 amp fused jumper wire from the positive terminal of the battery to relay terminal 1. Connect a jumper wire from the negative terminal of the battery to relay terminal 2. Measure for less than 2 ohms between terminals 3
and 5 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.
