For 1990-2009 cars

### 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.

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 |

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 Testing for Intermittent Conditions and Poor Connections

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 .
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 19

Go to Step 22

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 . Did you find and correct the condition? | Go to Step 27 | Go to Step 26
8 | Test the control circuit of the fuel pump relay for a short to ground, an open, or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 27 | Go to Step 20
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 21

Go to Step 25

11 | Inspect the fuel pump fuse. Is the fuse open? | Go to Step 12 | Go to Step 14
12 |

1. Test the supply voltage circuit of the fuel pump for a short to ground between the fuel pump fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs .
2. Replace the fuel pump fuse if necessary.

Did you find and correct the condition?

Go to Step 27

Go to Step 13

13 |

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

Is the fuel pump fuse open?

Go to Step 24

Go to Testing for Intermittent Conditions and Poor Connections

14 |

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

Does the test lamp illuminate?

Go to Step 15

Go to Step 23

15 | Connect a 15-amp fused jumper wire between the battery voltage circuit of the fuel pump relay and the supply voltage circuit of the fuel pump. Does the fuel pump operate? | Go to Step 19 | Go to Step 16
16 | Test the supply voltage circuit of the fuel pump for an open or high resistance between the fuel pump relay and the fuel pump. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 27 | Go to Step 17
17 | Important: Inspect the ground circuit for correct tightening, corrosion on the terminals, or damage to the wiring harness. Test the ground circuit of the fuel pump for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 27 | Go to Step 18
18 | Test for an intermittent and for a poor connection at the fuel tank module cover. 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 24
19 | 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 . Did you find and correct the condition? | Go to Step 27 | Go to Step 25
20 | Test for an intermittent and for a poor connection at 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 short to voltage in the supply voltage circuit of the fuel pump. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 27 | --
22 | Repair the open or high resistance in the ground circuit of the fuel pump relay . Refer to Wiring Repairs . Did you complete the repair? | Go to Step 27 | --
23 | Repair the open in the battery voltage circuit of the fuel pump relay. 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 Module Replacement .
2. Replace the fuel pump fuse if necessary.

Did you complete the replacement?

Go to Step 27

--

25 | Replace the fuel pump relay. Did you complete the replacement? | Go to Step 27 | --
26 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. 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