The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

The following conditions may cause the fuel pump fuse to open:

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Note: An open or a short to voltage in the control circuit will cause both the Ckt. Open Test Status and the Ckt. Short Volts Test Status parameters to display Fault.

Ignition ON, command the fuel pump relay ON and OFF with a scan tool while observing the following control circuit status parameters:

Each parameter should toggle between OK and Not Run or Not Run and OK.

1. With the ignition OFF, remove the fuel pump relay from the rear electrical center.
2. Test for less than 5 ohms between the ground circuit and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the fuel pump relay control circuit and the ground circuit. Command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lam pis always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Inspect the fuel pump fuse.

⇒	If the fuel pump fuse is open, test for the following conditions:

•	A short to ground in the relay switch B+ circuit

•	A short to ground in the supply voltage circuit of the fuel pump

⇒	If the above circuits test normal, replace the fuel sender.

5. Verify that a test light illuminates between the B+ circuit and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

6. Connect a 15A fused jumper wire between the B+ circuit and the supply voltage circuit of the fuel pump. Verify the fuel pump is activated.

⇒	If the fuel pump does not activate, 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 circuits test normal, replace the fuel sender.

7. If all circuits test normal, test or replace the fuel pump relay.

1. Measure for 70-100 ohms between terminals 85 and 86 of the fuel pump relay.

⇒	If the resistance is not within the specified range, replace the fuel pump relay.

2. Measure for infinite resistance between the following terminals of the fuel pump relay:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If continuity is detected, replace the fuel pump relay.

3. Connect a 15A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay.

⇒	If the resistance measures more than 2 ohms, replace the fuel pump relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.