GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - FWD 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Fuel Pump Electrical Circuit Diagnosis

Circuit Description

When the ignition switch is turned ON, the powertrain control module (PCM) energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain ON as long as the engine is running or cranking and the PCM is receiving crankshaft position (CKP) sensor reference pulses. If no CKP sensor reference pulses are present, the PCM de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON or the engine is stopped.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Command both the ON and OFF states. Repeat the commands as necessary. This can be determined by listening for an audible hiss from the fuel pump when the fuel pump relay is commanded ON or a vibration in the fuel feed line.

    2.

  2. This step determines if the condition is located on the coil side or the switch side of the relay.

    3.

  3. This step determines if the fuel pump relay is stuck closed.

    4.

  4. This step tests for a grounded voltage supply circuit. The fuel pump fuse supplies power to fuel pump. Disconnecting the fuel pump in-line harness connector isolates the fuel pump voltage supply circuit.

    5.

  5. This step verifies that the PCM is providing voltage to the fuel pump relay.

    6.

  6. This step verifies that the fuel pump fuse is providing voltage to the fuel pump relay.

    7.

  7. This step tests for an open circuit or a short to ground causing an open MaxiFuse.

    8.

  8. This step bypasses the fuel pump relay in order to activate the fuel pump.

    9.

  9. This step tests for an open in the fuel pump feed circuit between the in-line connector and the fuel pump relay.

    10.

  10. This step tests for an open or high resistance in the fuel pump ground circuit.

    11.

  11. 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.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain 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

2

Is DTC P0628 or P0629 present?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump relay ON and OFF with a scan tool.

Does the fuel pump turn ON and OFF?

Go to Intermittent Conditions

Go to Step 4

4

Important: An audible click should be heard.

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

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

Go to Step 5

Go to Step 10

5

Turn ON the ignition, with the engine OFF.

Does the fuel pump operate continuously?

Go to Step 6

Go to Step 7

6

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

Does the fuel pump operate continuously?

Go to Step 21

Go to Step 25

7

Is the fuel pump fuse open?

Go to Step 8

Go to Step 11

8

  1. Disconnect the fuel pump harness in-line connector located near the fuel tank.
  2. Test the supply voltage circuit of the fuel pump for a grounded circuit. Refer to Wiring Repairs and Connector Repairs .
  3. Replace the fuel pump fuse if necessary.

Did you find and correct the condition?

Go to Step 27

Go to Step 9

9
  1. Lower the fuel tank if necessary. Refer to Fuel Tank Replacement .
  2. Test or inspect the fuel tank electrical harness for the following conditions:
    3. • Damage to the harness
    • A grounded fuel pump voltage supply circuit--Refer to Circuit Testing and Wiring Repairs .
  3. Replace the fuel pump fuse if necessary.

Did you find and correct the condition?

Go to Step 27

Go to Step 18

10

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the fuel pump relay control circuit with a test lamp connected to a ground.
  5. Command the fuel pump ON and OFF with a scan tool.

Did the test lamp illuminate?

Go to Step 19

Go to Step 20

11

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the fuel pump relay with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 12

12

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump fuse.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive side of the fuel pump fuse, with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 22

Go to Step 23

13

Connect a 10-amp fused jumper wire between the battery positive voltage circuit and the fuel pump supply circuit in the fuel pump relay cavity.

Does the fuel pump operate?

Go to Step 19

Go to Step 14

14

  1. Disconnect the fuel pump harness in-line connector located near the fuel tank.
  2. Test the supply voltage circuit of the fuel pump for an open or for high resistance between the fuel pump relay and the in-line connector. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 15

15

Important: Inspect the fuel pump ground circuit for being tight, corrosion on the terminals, or damage to the wiring harness.

Test the ground circuit of the fuel pump for an open or for high resistance between the body pass through connector and the ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 16

16

Inspect for poor connections at the fuel pump in-line connector to the body pass through connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 17

17

  1. Lower the fuel tank. Refer to Fuel Tank Replacement .
  2. Test or inspect the fuel tank electrical harness for the following conditions:
    3. • Damage to the harness
    • A short to ground
    • An open circuit--Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 24

18
  1. Connect all disconnected components.
  2. Install a new fuel pump fuse.
  3. Command the fuel pump ON with a scan tool.

Is the fuel pump fuse open?

Go to Step 24

Go to Intermittent Conditions

19

Inspect for poor connections at the fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 25

20

Inspect for poor connections at the harness of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 27

Go to Step 26

21

Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 27

--

22

Repair the battery positive voltage circuit of the fuel pump relay for an open. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 27

--

23

Repair the battery positive voltage circuit of the fuel pump fuse for an open or a short to ground. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 27

--

24

Important: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.

  1. Replace the fuel tank module. Refer to Fuel Tank Replacement .
  2. Replace the fuel pump fuse if necessary.

Did you complete the replacement?

Go to Step 27

--

25

Replace the fuel pump relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 27

--

26
  1. Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .

Did you complete the replacement?

Go to Step 27

--

27

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2