GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Corvette 🢒 Engine 🢒 Engine Electrical 🢒 Fuel Pump Electrical Circuit Diagnosis

Circuit Description

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.

Diagnostic Aids

Fuel Pump Relay Underhood Electrical Center Terminal Identification

Front of Vehicle

Left Side of Vehicle

Ground

Ignition 1

Right Side of Vehicle

Fuel Pump Supply

Control

The following conditions may have caused the fuel pump fuse to open:

    • The fuse was faulty.
    • There is an intermittent short in the supply voltage circuit of the fuel pump.
    • The fuel pump has an internal intermittent condition.

For an intermittent condition, refer to Intermittent Conditions .

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump relay ON and OFF with a scan tool.
  3. Repeat the commands as necessary.

Does the fuel pump turn ON and OFF?

Go to Diagnostic Aids

Go to Step 3

3

Command the fuel pump relay ON and OFF with a scan tool.

Do you hear the fuel pump relay click when you command the fuel pump relay ON and OFF?

Go to Step 9

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
  5. Command the fuel pump relay ON and OFF with a scan tool.

Does the test lamp turn ON and OFF?

Go to Step 5

Go to Step 6

5

  1. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
  2. Command the fuel pump relay ON and OFF with a scan tool.

Does the test lamp turn ON and OFF?

Go to Step 21

Go to Step 25

6

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 8

7

Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 29

8

Test the control circuit of the fuel pump relay for a short to ground and for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 22

9

Turn ON the ignition, with the engine OFF.

Does the fuel pump operate continuously?

Go to Step 10

Go to Step 11

10
  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.

Does the fuel pump operate continuously?

Go to Step 24

Go to Step 28

11

Inspect the F/PMP fuse.

Is the fuse open?

Go to Step 12

Go to Step 15

12

  1. Remove the left rear wheel house panel. Refer to Rear Wheelhouse Panel Liner Replacement in Body Rear End.
  2. Disconnect the fuel pump harness in-line connector. Refer to Inline Harness Connector End Views in Wiring Systems.
  3. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  4. Replace the F/PMP fuse if necessary.

Did you find and correct the condition?

Go to Step 30

Go to Step 13

13
  1. Remove the left fuel tank. Refer to Fuel Tank Replacement - Left Side .
  2. Inspect the fuel sender harness on top of the fuel tank for the following conditions:
    3. • Any damage to the harness
    • A short to ground in the supply voltage circuit of the fuel pump--Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. Replace the F/PMP fuse if necessary.

Did you find and correct the condition?

Go to Step 30

Go to Step 14

14

  1. Install all removed electrical components.
  2. Install a new F/PMP fuse.
  3. Command the fuel pump relay ON with a scan tool.
  4. Inspect the F/PMP fuse.

Is the fuse open?

Go to Step 23

Go to Intermittent Conditions

15
  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the fuel pump relay, switch side, with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

Go to Step 16

Go to Step 26

16

Connect a 20-amp fused jumper wire between the ignition 1 voltage circuit of the fuel pump relay and the supply voltage circuit of the fuel pump.

Does the fuel pump operate?

Go to Step 21

Go to Step 17

17

  1. Remove the left rear wheelhouse panel. Refer to Rear Wheelhouse Panel Liner Replacement in Body Rear End.
  2. Disconnect the fuel pump harness in-line connector. Refer to Inline Harness Connector End Views in Wiring Systems.
  3. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for an open and for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 18

18

Important: Inspect the ground circuit for proper torque, corrosion on the terminals, and damage to the wiring harness.

Test the ground circuit of the fuel pump for an open and for high resistance between the fuel pump harness in-line connector and ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 19

19

Test for an intermittent and for a poor connection at the fuel pump harness in-line connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 20

20
  1. Remove the left fuel tank. Refer to Fuel Tank Replacement - Left Side .
  2. Inspect the fuel sender harness on top of the fuel tank for the following conditions:
    3. • Any damage to the harness
    • An open circuit--Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 23

21

Test for an intermittent and for a poor connection at the fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 28

22

Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 29

23

Test for an intermittent and for a poor connection at the fuel pump connector within the fuel tank. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 27

24

Repair the short to voltage in the supply voltage circuit of the fuel pump. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 30

--

25

Repair the open or high resistance in the ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 30

--

26

Repair the open in the ignition 1 voltage circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 30

--

27
  1. Replace the fuel pump. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side or Fuel Tank Fuel Pump Module Replacement - Right Side .
  2. Replace the F/PMP fuse if necessary.

Did you complete the replacement?

Go to Step 30

--

28

Replace the fuel pump relay.

Did you complete the replacement?

Go to Step 30

--

29

Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 30

--

30

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2