Fuel Pump Control
Fuel Pump Circuit:
Power to the fuel pump is controlled by the ECM through the control relays. See CONTROL RELAY.
Fuel Pump Test Connector Usage:
OPERATION TEST
To test the pump operation, connect a 12 Volt power source to the pump test connector (located on the firewall, near the battery). Remove the fuel cap and listen through the fuel filler neck for the sound of the pump. If the pump operates during the operational test, continue with the harness test. If no pump sound is heard, check the ground circuit (step #1) and also test the control relay see CONTROL RELAY. If no faults are found, replace the fuel pump.
RESISTOR TEST
1. Disconnect the resistor harness connector.
2. Measure the resistance between the resistor connector terminals.
Resistance:
0.6 - 0.9 Ohms.
If the resistor value is out of specification, it should be replaced.
Control Relay (For Fuel Pump) Testing:
CONTROL RELAY (FOR FUEL PUMP) TEST
Refer to image for testing procedure. Replace relay if it is found to be defective.
HARNESS TEST
1. Disconnect the fuel pump connector located on the fuel tank. Using an Ohmmeter, check the ground circuit of the fuel pump between the harness connector terminal 2 and ground.
Continuity:
Should exist.
2. Using an Ohmmeter, check for continuity between the fuel pump check connector and the fuel pump harness connector terminal 1.
Continuity:
Should exist.
3. Disconnect the control relay (for fuel pump) harness connector.
4. Disconnect the fuel pump resistor harness connector.
5. Using an Ohmmeter, check for continuity between the fuel pump check terminal and both the control relay (for fuel pump) harness terminal 4 and fuel pump resistor harness connector terminal 2.
Continuity:
Should exist.
6. With the ignition "OFF" disconnect the ECM harness connector.
7. Using an Ohmmeter, check for continuity between the ECM harness connector terminal 21 and control relay (for fuel pump) harness connector terminal 1.
Continuity:
Should exist.
8. Using an Ohmmeter, check for continuity (short to ground) between the ECM harness connector terminal 21 and ground.
Continuity:
Should not exist.
9. Using an Ohmmeter, check for continuity (short to ground) between the control relay (for fuel pump) harness connector terminal 1 and ground.
Continuity:
Should not exist.
10. Using an Ohmmeter, check for continuity between control relay (for fuel pump) harness terminal 4 and resistor harness connector terminal 1.
Continuity:
Should exist.
11. Turn the key to the "ON" position. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage between the control relay harness connector terminal 3 and ground.
Voltage:
8 or more volts.
12. Turn the key to the START position. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage between the control relay harness connector terminal 9 and ground.
Voltage:
8 or more volts.
13. Turn the key to the OFF position. Measure the supply voltage of the control relay from the battery. Using a voltmeter, measure the voltage between the control relay connector terminal 10 and ground.
Voltage:
System voltage.
14. Using an Ohmmeter, check for continuity between the control relay harness connector terminal 7 and ground.
Continuity:
Should not exist.
15. Using an Ohmmeter, check for continuity between the ECM harness connector terminal 8 and ground.
Continuity:
Should not exist.
16. Using an Ohmmeter, check for continuity between the ECM harness connector terminal 8 and the control relay harness connector terminal 7.
Continuity:
Should exist.
17. Using an Ohmmeter, check for continuity (short to ground) between the control relay terminal 2 and ground.
Continuity:
Should not exist.
18. Using an Ohmmeter, check for continuity to ground (short to ground) between the control relay (for fuel pump) terminals 3 and 5.
Continuity:
Should not exist.
19. Using an Ohmmeter, check for continuity of the ground circuit between the control relay harness connector terminal 6 and ground.
Continuity:
Should exist.
20. Using an Ohmmeter, check for continuity between the control relay (for fuel pump) terminal 1 and the fuel pump connector 2.
Continuity:
Should exist.
21. Using an Ohmmeter, check for continuity (short to ground) between the control relay (for fuel pump) terminal 1 and ground.
Continuity:
Should not exist.
22. Using an Ohmmeter, check for continuity (short to ground) fuel pump connector 2 and ground.
Continuity:
Should not exist.
If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.
If the problem returns, it is possible that there is an intermittent failure of the component or the ECM. Check for looseness at all harness junctions and test for an intermittent failure. If the same trouble code reoccurs, the ECM will need to be changed.