Circuit Description
When the ignition is turned ON, the powertrain control module (PCM) turns ON the fuel pump relay, which turns ON the in-tank fuel pump. The in-tank fuel pump remains 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 turns the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the PCM no longer receives reference pulses.
Diagnostic Aids
| • | Inspect the ground connection for the fuel pump. Ensure all ground connections are clean and tight. |
| • | The following conditions may have caused the fuel pump fuse to open: |
| - | The fuse is faulty. |
| - | There is an intermittent short in the fuel pump power feed circuit. |
| - | The fuel pump has an intermittent internal problem. |
| • | 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.
-
This step determines if the condition is located on the coil side or the switch side of the circuit.
-
This step verifies that the PCM is providing voltage to the fuel pump relay.
-
This step tests for an open in the ground circuit to the fuel pump relay.
-
This step determines if a voltage is constantly being applied to the fuel pump relay.
-
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.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Component 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? | 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 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 . 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 . 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 Testing for Intermittent Conditions and Poor Connections | |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 23 |
15 | Connect a 10-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 . Did you find and correct the condition? | Go to Step 27 | 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 . 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 . 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 . 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 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 supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 27 | -- |
22 | Repair the open fuel pump relay ground circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 27 | -- |
23 | Repair the battery voltage circuit of the fuel pump relay switch. 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.
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 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
