Non Trouble Code Components

System Schematic:

Power to the fuel pump is controlled by the ECU through the control relay. To test the relay refer to the CONTROL RELAY test procedure located in TESTING PROCEDURES.

To test the pump operation, connect a 12 Volt power source to the pump test connector. Remove the fuel cap and listen through the fuel filler neck for the sound of the pump. If no pump sound is heard, refer to POWER SUPPLY testing procedures located in TESTING PROCEDURES.


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 1 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 2.

Continuity: Should Exist.

3. Disconnect control relay connector. Using an Ohmmeter, check for continuity between the check connector and the control relay harness connector terminal 1.

Continuity: Should Exist.

4. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage at the control relay harness connector terminal 8 with the ignition switch in the on position.

Voltage: 8 Or More Volts.


5. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage at the control relay harness connector terminal 6 and the ECU harness connector terminal 55 with the ignition switch in the start position.


Voltage: 8 Or More Volts.

6. Using an Ohmmeter, check for continuity (shorts) to ground, between the ECU harness connector terminal 51, the control relay harness connector terminal 5, the ECU harness connector terminal 22 and the control relay harness connector terminal 2.

Continuity: Should Not Exist.

7. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 51 and the control relay harness connector terminal 5. The ECU harness connector terminal 22 and the control relay harness connector terminal 2.

Continuity: Should Exist.

8. Using an Ohmmeter, check for continuity of the ground circuit between the control relay harness connector terminal 4 and ground.

Continuity: Should Exist.

9. Using an Ohmmeter, check for continuity (short) to ground between the control relay harness connector terminal 1 and the fuel pump harness connector 2.

Continuity: Should Not Exist.


10. Using an Ohmmeter, check for continuity between the control relay harness connector terminal 1 and the fuel pump harness connector 2.

Continuity: Should 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.
If the same problem reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.