Circuit Description
When the ignition is turned ON, the powertrain control module (PCM) will turn ON the in-tank fuel pump. The in-tank fuel pump will remain ON as long as the engine is cranking or running and the PCM is receiving reference pulses. If there are no reference pulses, the PCM will turn the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the engine stops running.
Diagnostic Aids
A fuel pump prime terminal is available at the underhood bussed electrical center (UBEC). Refer to the UBEC cover for terminal location.
The following conditions may have caused the fuel pump circuit breaker to open:
| • | The fuel pump circuit breaker is faulty. |
| • | There is an intermittent short in the fuel pump power feed circuit. |
| • | The fuel pump has an intermittent internal condition. |
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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Command both the ON and OFF states. Repeat the commands as necessary.
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This step determines if the condition is located on the coil side or the switch side of the circuit.
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This step verifies that the 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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To gain access to the fuel pump connector, the fuel tank may need to be removed.
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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.
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Use the same amperage fuse in the jumper as is used to protect the fuel pump circuit.
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To gain access to the fuel pump connector, the fuel tank may need to be removed.
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Inspect the ground connection for the fuel pump. Be certain all ground connections are clean and tight.
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 | |
Does the fuel pump turn ON and OFF? | Go to Diagnostic Aids | Go to Step 3 | |
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 9 | Go to Step 4 | |
Does the test lamp turn ON and OFF? | Go to Step 5 | Go to Step 6 | |
Does the test lamp turn ON and OFF? | Go to Step 20 | Go to Step 23 | |
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 29 | Go to Step 28 |
8 | Test the control circuit of the fuel pump relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 21 |
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 22 | Go to Step 26 |
11 |
Does the fuel pump operate? | Go to Step 27 | Go to Step 12 |
12 | Inspect the fuse in the jumper harness. Is the fuse open? | Go to Step 13 | Go to Step 15 |
Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump circuit breaker and the fuel pump. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 14 | |
Is the fuse in the jumper harness open? | Go to Step 25 | Go to Testing for Intermittent Conditions and Poor Connections | |
15 |
Does the test lamp illuminate? | Go to Step 16 | Go to Step 24 |
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 20 | Go to Step 17 | |
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 29 | Go to Step 18 | |
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 29 | Go to Step 19 | |
19 | Inspect for poor connections at the fuel pump. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 25 |
20 | Inspect for poor connections at 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 29 | Go to Step 26 |
21 | Inspect for poor connections 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 29 | Go to Step 28 |
22 | 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 29 | -- |
23 | Repair the open fuel pump relay ground circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 29 | -- |
24 | Repair the battery voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 29 | -- |
25 |
Important: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.
Did you complete the replacement? | Go to Step 29 | -- |
26 |
Important: Test the fuel pump prime circuit for a short to voltage before replacing the fuel pump relay. Replace the fuel pump relay. Did you complete the replacement? | Go to Step 29 | -- |
27 |
Important: Inspect for poor connections at the fuel pump circuit breaker. Replace the fuel pump circuit breaker. Did you complete the replacement? | Go to Step 29 | -- |
28 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 29 | -- |
29 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
