Fuel Pump Electrical Circuit Diagnosis
CIRCUIT DESCRIPTIONWhen the ignition is turned ON, the Powertrain Control Module (PCM) turns ON the in-tank fuel pump. The in-tank fuel pump remains ON as long as the engine is cranking or running and the PCM is receiving ignition reference pulses. If there are no ignition reference pulses, the PCM will turn the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the engine stops running.
TEST DESCRIPTION
Steps 1-13:
Steps 14-27:
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 PCM is providing voltage to the fuel pump relay.
5. This step tests for an open in the ground circuit to the fuel pump relay.
6. This step determines if a voltage is constantly being applied to the fuel pump relay.
13. 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.
15. Use the same amperage fuse in the jumper as is used to protect the fuel pump circuit.
17. Inspect the splice pack which contains the fuel pump ground and other ground circuits. Be certain all connections within the splice pack are clean and tight.