Relay - Test - Fuel Lift Pump Relay
This procedure covers the following diagnostic codes:
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| Diagnostic Trouble Codes for the Fuel Lift Pump Relay | ||
|---|---|---|
| J1939 Code | Code Description | Comments |
| 1075-3 | Engine Electric Lift Pump for Engine Fuel Supply : Voltage Above Normal | The Electronic Control Module (ECM) detects a high voltage condition (open circuit) in the fuel lift pump relay control circuit. |
| 1075-4 | Engine Electric Lift Pump for Engine Fuel Supply : Voltage Below Normal | The Electronic Control Module (ECM) detects a low voltage condition (short circuit) in the fuel lift pump relay control circuit. |
| Follow the troubleshooting procedure to identify the root cause of the fault. | ||
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| Illustration 1 | g06100297 |
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Schematic for the fuel lift pump relay | |
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| Illustration 2 | g06028408 |
Complete the procedure in the order in which the steps are listed.
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
1. Inspect Electrical Connectors and Wiring A. Inspect the terminals on the fuel lift pump relay. Refer to Troubleshooting, "Electrical Connector - Inspect" for details. B. Perform a C. Check the harness for abrasion and pinch points from the fuel lift pump relay back to the ECMs. |
Loose connection or damaged wire |
Result: There is a fault in a connector or the wiring. Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. The fuses are not blown. Proceed to Test Step 2. |
2. Check for Active Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. Note: Do not start the engine. C. Use the electronic service tool to check for active diagnostic codes. D. Turn the keyswitch to the OFF position. |
Diagnostic codes |
Result: Diagnostic code 1075-3 is active or recently logged. Proceed to Test Step 3. Result: Diagnostic code 1075-4 is active or recently logged. Proceed to Test Step 6. |
3. Check the Supply Voltage at the Fuel Lift Pump Relay Connector A. Remove the fuel lift pump relay. B. Measure the voltage between Test Point 2 on the relay connector and a suitable ground. C. Turn the keyswitch to the OFF position. D. Install the fuel lift pump relay. |
At least 11 VDC |
Result: The voltage is not within the expected range. Repair: Repair or replace the supply wiring to the fuel lift pump relay. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The voltage is within the expected range. Proceed to Test Step 4. |
4. Check the Return Wire from the Fuel Lift Pump Relay to the Engine ECM A. Turn the keyswitch to the OFF position. B. Remove the fuel lift pump relay. C. Disconnect the P2 connector from the engine ECM. D. Measure the resistance between Test Point 1 on the fuel lift pump relay connector and P2:93. E. Connect the P2 connector to the engine ECM. F. Install the fuel lift pump relay. |
Less than 2.0 Ohms |
Result: The measured resistance is more than 2.0 Ohms. Repair: Repair or replace the return wiring from the fuel lift pump relay. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The measured resistance is less than 2.0 Ohms. Proceed to Test Step 5. |
5. Check the Fuel Lift Pump Relay Solenoid for an Open Circuit A. Verify that the keyswitch is in the OFF position. B. Remove the fuel lift pump relay. C. Measure the resistance between Test Points 1 and 2 on the fuel lift pump relay. Refer to Illustration 2. D. Install the fuel lift pump relay. |
81 Ohms to 113 Ohms |
Result: The measured resistance is more than 81 Ohms to 133 Ohms. Repair: Install a replacement fuel lift pump relay. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The measured resistance is within 81 Ohms to 133 Ohms. Contact the Dealer Solutions Network (DSN). |
6. Check the Wiring for a Short Circuit A. Turn the keyswitch to the OFF position. B. Remove the fuel lift pump relay. C. Disconnect the P2 connector from the engine ECM. D. Check the resistance between P2:93 and all other pins on the P2 connector for the engine ECM. E. Reconnect the P2 connector to the engine ECM. F. Install the fuel lift pump relay. |
More than 1k Ohm |
Result: One or more resistance measurements are less than 1k Ohm. Repair: Repair or replace the wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are more than 1k Ohm. Proceed to Test Step 7. |
7. Check the Fuel Lift Pump Relay Solenoid for a Short Circuit A. Verify that the keyswitch is in the OFF position. B. Remove the fuel lift pump relay. C. Measure the resistance between Test Points 1 and 2 on the fuel lift pump relay. Refer to Illustration 2. D. Install the fuel lift pump relay. |
81 Ohms to 113 Ohms |
Result: The measured resistance is less than 81 Ohms to 133 Ohms. Repair: Install a replacement fuel lift pump relay. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The measured resistance is within 81 Ohms to 133 Ohms. Proceed to Test Step 8. |
8. Perform a Fuel Lift Pump Relay Override Test A. Turn the keyswitch to the ON position. B. Use the electronic service tool to perform the Fuel Lift Pump Relay Override Service Test. C. Check the operation of the fuel lift pump. D. Stop the Fuel Lift Pump Relay Override Service Test. E. Turn the keyswitch to the OFF position. |
Battery voltage |
Result: The fuel lift pump operates correctly. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The fuel lift pump does not operate correctly. Contact the Dealer Solutions Network (DSN). |
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