Circuit Description
When you turn ON the ignition switch, the control module energizes the fuel pump relay which powers the fuel pump ON. The pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.
Diagnostic Aids
The following conditions may have caused the fuel pump fuse to open:
| • | The fuse is faulty. |
| • | There is an intermittent short to ground in the fuel pump battery voltage circuit. |
| • | The fuel pump has an intermittent internal condition. |
For an intermittent condition, refer to Intermittent Conditions .
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 fuel pump relay.
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This step verifies that the PCM is providing voltage to the control circuit of 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 control circuit of the fuel pump relay.
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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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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: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Does the fuel pump turn ON and OFF? | Go to Intermittent Conditions | 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 19 | Go to Step 22 | |
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 27 | Go to Step 26 |
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 in Wiring Systems. 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 |
Does the fuel pump operate continuously? | Go to Step 21 | Go to Step 25 |
11 | 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 27 | Go to Step 13 |
Is the fuel pump fuse open? | Go to Step 24 | Go to Diagnostic Aids | |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 23 |
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 for an open or high resistance between the fuel pump relay and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 27 | Go to Step 17 |
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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 in Wiring Systems. Did you find and correct the condition? | Go to Step 27 | Go to Step 18 | |
18 | Inspect for poor connections at the fuel pump. 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 27 | Go to Step 24 |
19 | Inspect for poor connections 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 27 | Go to Step 25 |
20 | Inspect for poor connections at the harness connector of the PCM. 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 27 | Go to Step 26 |
21 | Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 27 | -- |
22 | Repair the open in the ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 27 | -- |
23 | Repair the open in the battery voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs in Wiring Systems. 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.
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 Powertrain Control Module Replacement . 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 |
