Circuit Description
When you turn ON the ignition switch, the control module enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition 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.
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 current.
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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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This step determines if the condition with the circuit is intermittent.
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This step determines if the fuel pump will operate while by-passing the fuel pump relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Does the fuel pump relay click when commanded with a scan tool? | Go to Intermittent Conditions | Go to Step 3 | |
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 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 21 | |
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 in Wiring Systems. Did you find and correct the condition? | Go to Step 25 | Go to Step 24 |
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 25 | 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 | Test the supply voltage circuit of the fuel pump 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 25 | Go to Step 23 |
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 25 | Go to Step 13 |
Is the fuel pump fuse open? | Go to Step 22 | Go to Intermittent Conditions | |
14 | Test the battery voltage circuit of the fuel pump relay switch for an open. Refer to Circuit Testing and Wiring Repairs Did you find and correct the condition? | Go to Step 25 | Go to Step 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 between the fuel pump relay and 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 25 | 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 high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 25 | 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 25 | Go to Step 22 |
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 25 | Go to Step 23 |
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 25 | Go to Step 24 |
21 | Repair the open fuel pump relay ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 25 | -- |
22 |
Important: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you complete the replacement? | Go to Step 25 | -- |
23 | Replace the fuel pump relay. Did you complete the replacement? | Go to Step 25 | -- |
24 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 25 | -- |
25 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
