When the ignition switch is turned ON, the engine control module (ECM) energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain on as long as the engine is running or cranking and the ECM is receiving crankshaft position (CKP) sensor reference pulses. If no CKP sensor reference pulses are present, the ECM de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON or the engine is stopped. The ECM applies a low current signal of approximately 7 volts to the fuel pump relay control circuit with the key ON and the engine OFF. The ECM uses this signal to detect the integrity of the fuel pump relay control circuit.
Fuel Relay Underhood Bussed Electrical Center Terminal Identification | |||
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Right side of vehicle | Ground | Fuel pump supply | Left side of vehicle |
-- | Battery positive voltage | Control | -- |
Front of vehicle |
The numbers below refer to the step numbers on the diagnostic table:
Command both the ON and OFF states. Repeat the commands as necessary. This can be determined by listening for an audible hiss from the fuel pump when the fuel pump relay is commanded ON or a vibration in the fuel feed line.
This step determines if the condition is located on the coil side or the switch side of the relay.
This step determines if the fuel pump relay is stuck closed.
This step tests for a grounded voltage supply circuit. The fuel pump fuse supplies power to fuel pump. Disconnecting the fuel pump in-line harness connector isolates the fuel pump voltage supply circuit.
This step verifies that the ECM is providing voltage to the fuel pump relay.
This step verifies that the fuel pump fuse is providing voltage to the fuel pump relay.
This step tests for an open circuit or a short to ground causing an open MaxiFuse.
This step bypasses the fuel pump relay in order to activate the fuel pump.
This step tests for an open in the fuel pump feed circuit between the in-line connector and the fuel pump relay.
This step tests for an open or high resistance in the fuel pump ground circuit.
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 | ||||||
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Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls 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 | |||||||
Important: An audible click should be heard. 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 4 | Go to Step 9 | |||||||
4 | Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously? | Go to Step 5 | Go to Step 6 | ||||||
Does the fuel pump operate continuously? | Go to Step 20 | Go to Step 24 | |||||||
6 | Is the fuel pump fuse open? | Go to Step 7 | Go to Step 10 | ||||||
Did you find and correct the condition? | Go to Step 26 | Go to Step 8 | |||||||
8 |
Did you find and correct the condition? | Go to Step 26 | Go to Step 17 | ||||||
Did the test lamp illuminate? | Go to Step 18 | Go to Step 19 | |||||||
Does the test lamp illuminate? | Go to Step 12 | Go to Step 11 | |||||||
Does the test lamp illuminate? | Go to Step 21 | Go to Step 22 | |||||||
Connect a 10-amp fused jumper wire between the battery positive voltage circuit and the fuel pump supply circuit in the fuel pump relay cavity. Does the fuel pump operate? | Go to Step 18 | Go to Step 13 | |||||||
Did you find and correct the condition? | Go to Step 26 | Go to Step 14 | |||||||
14 |
Important: Inspect the fuel pump ground circuit for being tight, corrosion on the terminals, or damage to the wiring harness. Test the ground circuit of the fuel pump for an open or for high resistance between the body pass through connector and the ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 26 | Go to Step 15 | ||||||
15 | Inspect for poor connections at the fuel pump in-line connector to the body pass through connector. 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 26 | Go to Step 16 | ||||||
Did you find and correct the condition? | Go to Step 26 | Go to Step 23 | |||||||
17 |
Is the fuel pump fuse open? | Go to Step 23 | Go to Intermittent Conditions | ||||||
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 26 | Go to Step 24 | |||||||
19 | Inspect for poor connections at the harness of the engine control module (ECM). 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 26 | Go to Step 25 | ||||||
20 | 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 26 | -- | ||||||
21 | Repair the battery positive voltage circuit of the fuel pump relay for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 26 | -- | ||||||
22 | Repair the battery positive voltage circuit of the fuel pump fuse for an open or a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 26 | -- | ||||||
23 |
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 26 | -- | ||||||
24 | Replace the fuel pump relay. Refer to Relay Replacement in Wiring Systems. Did you complete the replacement? | Go to Step 26 | -- | ||||||
25 | Replace the engine control module (ECM). Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 26 | -- | ||||||
26 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |