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 two 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 two seconds if ignition reference pulses cease to be detected and the ignition remains ON.
Diagnostic Aids
A fuel pump prime terminal is located at the underhood bussed electrical center (UBEC). Refer to the UBEC cover for terminal location.
The following conditions may have caused the fuel pump fuse to open:
| • | A faulty fuse |
| • | An intermittent short in the fuel pump power supply circuit |
| • | An intermittent internal component failure |
For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the condition is located on the coil side or on the switch side of the fuel pump relay.
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This step verifies that the powertrain control module (PCM) is providing voltage to the fuel pump relay.
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This step tests for an open in the ground circuit to the fuel pump relay.
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This step determines if a voltage is constantly being applied to the fuel pump relay.
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This step determines if the condition with the circuit is intermittent.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the fuel pump turn ON and OFF when commanded with a scan tool? | Go to Diagnostic Aids | Go to Step 3 |
Command the fuel pump relay ON and OFF with a scan tool. Does the fuel pump relay turn ON and OFF when commanded with a scan tool? | Go to Step 9 | Go to Step 4 | |
Does the test lamp turn ON and OFF when commanded with a scan tool? | Go to Step 5 | Go to Step 6 | |
Does the test lamp turn ON and OFF when commanded with a scan tool? | Go to Step 19 | Go to Step 22 | |
Does the test lamp remain illuminated? | 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 28 | Go to Step 27 |
8 | Test the control circuit of the fuel pump relay for a short to ground or for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 28 | 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 |
Does the fuel pump operate continuously? | Go to Step 21 | Go to Step 26 |
11 | Inspect the fuel pump fuse. Is the fuel pump fuse open? | Go to Step 12 | Go to Step 14 |
12 |
Did you find and correct the condition? | Go to Step 28 | Go to Step 13 |
Is the fuel pump fuse open? | Go to Step 24 | Go to Testing for Intermittent Conditions and Poor Connections | |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 23 |
15 | Connect a 20-amp fused jumper wire between the battery voltage circuit of the fuel pump relay switch 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, between the fuel pump relay and the fuel pump for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 28 | Go to Step 17 |
17 |
Important: Inspect the ground circuit for being tight, corrosion on terminals, or damage to the wiring harness. Test the ground circuit of the fuel pump for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 28 | Go to Step 18 |
18 | Test for an intermittent or for a poor connection at the fuel pump sender assembly connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 28 | Go to Step 24 |
19 | Test for an intermittent or 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 28 | Go to Step 26 |
20 | Test for an intermittent and for a poor connection at the harness connector 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 28 | Go to Step 27 |
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 28 | -- |
22 | Repair the open in the fuel pump relay ground circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 28 | -- |
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 28 | -- |
24 | Test for an intermittent and for a poor connection at the fuel pump sender assembly connector within the fuel tank. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the conditions? | Go to Step 28 | Go to Step 25 |
25 |
Did you complete the replacement? | Go to Step 28 | -- |
26 | Replace the fuel pump relay. Did you complete the replacement? | Go to Step 28 | -- |
27 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 28 | -- |
28 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
