Fuel Pump Electrical Circuit Diagnosis
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.
Step
Action
Yes
No
Schematic Reference: Engine Controls Schematics
Connect End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check-Engine Controls?
Go to
Step 2
Go to
Diagnostic System Check - Engine Controls
2
- <LI type=1>Turn ON the ignition, with the engine OFF. <LI type=1>Command the fuel pump relay ON and OFF with a scan tool.
- Repeat the commands as necessary.
Does the fuel pump turn ON and OFF?
Go to
Intermittent Conditions
Go to
Step 3
3
Command the fuel pump relay ON and OFF with a scan tool.
Do you hear the fuel pump relay click when you command the fuel pump relay ON and OFF?
Go to
Step 9
Go to
Step 4
4
- <LI type=1>Turn OFF the ignition. <LI type=1>Remove the fuel pump relay. <LI type=1>Turn ON the ignition, with the engine OFF. <LI type=1>Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
- Command the fuel pump relay ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?
Go to
Step 5
Go to
Step 6
5
- <LI type=1>Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
- Command the fuel pump relay ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?
Go to
Step 19
Go to
Step 22
6
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
- <LI type=1>Turn OFF the ignition. <LI type=1>Remove the fuel pump relay.
- Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?
Go to
Step 21
Go to
Step 25
11
Inspect the F/P INJ fuse.
Is the F/P INJ fuse open?
Go to
Step 12
Go to
Step 14
12
Important: The F/P INJ fuse also supplies ignition voltage to the fuel injectors. Test all related circuits for a short to ground.
- <LI type=1>Test the supply voltage circuit of the fuel pump for a short to ground between the F/P INJ fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
- Replace the F/P INJ fuse if necessary.
Did you find and correct the condition?
Go to
Step 27
Go to
Step 13
13
- <LI type=1>Connect all disconnected electrical components. <LI type=1>Install a new FP INJ fuse. <LI type=1>Command the fuel pump relay ON with a scan tool.
- Inspect the FP INJ fuse.
Is the FP INJ fuse open?
Go to
Step 24
Go to
Intermittent Conditions
14
- <LI type=1>Turn OFF the ignition. <LI type=1>Remove the fuel pump relay. <LI type=1>Turn ON the ignition, with the engine OFF.
- Probe the ignition 1 voltage circuit of the fuel pump relay, switch side, with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
Go to
Step 15
Go to
Step 23
15
Connect a 15-amp fused jumper wire between the ignition 1 voltage circuit of the fuel pump relay 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
17
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
Test for an intermittent and for a poor connection at the fuel sender cover. 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
Test for an intermittent and for a poor connection 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
Test for an intermittent and for a poor connection at 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 short to voltage in the supply voltage circuit of the fuel pump. Refer to
Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to
Step 27
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22
Repair the open or high resistance 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
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23
Repair the open in the ignition 1 voltage circuit of the fuel pump relay. Refer to
Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to
Step 27
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24
Important: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.
- <LI type=1>Replace the fuel pump module. Refer to Fuel Pump Module Replacement .
- Replace the FP INJ fuse if necessary.
Did you complete the replacement?
Go to
Step 27
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25
Replace the fuel pump relay.
Did you complete the replacement?
Go to
Step 27
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26
Replace the PCM. Refer to
Powertrain Control Module (PCM) 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