Fuel Pump Electrical Circuit Diagnosis

FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS

CIRCUIT DESCRIPTION
When the ignition is turned ON, the engine control module (ECM) will turn ON the in-tank fuel pump. The in-tank fuel pump will remain ON as long as the engine is cranking or running and the ECM is receiving reference pulses. If there are no reference pulses, the ECM will turn the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the engine stops running.

DIAGNOSTIC AIDS
- The following conditions may have caused the fuel pump fuse to open:
- There is an intermittent short in the fuel pump supply voltage circuit.
- The fuel pump has an intermittent internal condition.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-12:

Steps 13-20:

The numbers below refer to the step numbers on the diagnostic table.
2. Command both the ON and OFF states. Repeat the commands as necessary.
3. This step determines if the condition is located on the coil side or the switch side of the circuit.
4. This step verifies that the battery positive is providing voltage is present at the fuel pump relay.
9. This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
11. Use the same amperage fuse in the jumper that is used in order to protect the fuel pump circuit.
13. Inspect the ground connection for the fuel pump. Be certain all ground connections are clean and tight.