C4.4 Marine Generator Set Caterpillar

Relay - Test - Electric Fuel Lift Pump Relay

Usage:

C4.4 NRP

This procedure covers the following codes:

Also, use this procedure if the Electric Fuel Lift Pump (EFLP) relay is not operating correctly.

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Table 1
Diagnostic Trouble Codes for the EFLP Relay
J1939 Code	Code Description	Comments
1075-5	Engine Electric Lift Pump for Engine Fuel supply: Current Below Normal	The Electronic Control Module (ECM) detects the following conditions: There are no active 168 diagnostic codes. The ECM is not attempting to power the relay. The ECM has been powered for at least 2 seconds. There is a low current condition in the EFLP relay circuit for more than 2 seconds. The warning light will come on. The diagnostic code will be logged. The ECM is unable to activate the relay for the EFLP. The EFLP will not operate or the EFLP will operate all the time. The engine will not operate.
1075-6	Engine Electric Lift Pump for Engine Fuel supply: Current Above Normal	The ECM detects the following conditions: There are no active 168 diagnostic codes. The ECM is attempting to power the relay. The ECM has been powered for at least 2 seconds. There is a high current condition in the EFLP relay circuit for more than 2 seconds. The warning light will come on. The diagnostic code will be logged. The ECM is unable to activate the relay for the EFLP. The EFLP will not operate or the EFLP will operate all the time. The engine will not operate. The ECM will continue to attempt to activate the relay. If the current is OK for 6 seconds, then the diagnostic code will be cleared.

The following background information is related to this procedure:

The EFLP is used in order to provide positive fuel pressure to the high-pressure fuel pump. When the isolator switch is turned to the ON position, battery power is supplied to activate the relay for the EFLP. If the engine is not running, the ECM will deactivate the relay for the EFLP after 2 minutes.

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Illustration 1	g03614199
Schematic of the circuit for the EFLP and relay

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Illustration 2	g02138993
View of the pin location on the P1 connector for the EFLP (21) Relay for the EFLP

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Check that the circuit breakers are not tripped. B. Inspect the terminals on the EFLP relay and the P1 ECM connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the EFLP relay. D. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). E. Check the harness for abrasion and pinch points from the EFLP relay back to the ECM and the isolator switch.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair any faulty connectors or replace the wiring harness. Ensure that all of 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 circuit breaker is not tripped. Proceed to Test Step 2.
2. Check for Active Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. B. Turn the isolator switch to the ON position. Note: Do not start the engine. C. Check for active diagnostic codes or recently logged diagnostic codes.	Diagnostic codes	Result: No diagnostic codes are present. There may be an intermittent fault in an electrical component between the ECM and the EFLP. The problem may be inside an electrical connector. Refer to Troubleshooting, "Electrical Connector - Inspect" in order to identify intermittent faults. If no connector faults are identified, proceed to Test Step 3. Result: A 1075-5 diagnostic code is active or recently logged. Proceed to Test Step 3. Result: A 1075-6 diagnostic code is active or recently logged. Proceed to Test Step 4.
3. Create a Short Circuit at the EFLP Relay Connector A. Turn the isolator switch to the OFF position. B. Remove the EFLP relay. C. Fabricate a jumper wire that is 150 mm (6 inch) long. Use the jumper wire to connect socket 1 to socket 2 on the harness connector for the EFLP relay. Refer to Illustration 1. D. Turn the isolator switch to the ON position. E. Use the electronic service tool to check for active diagnostic codes. Wait at least 30 seconds for activation of the diagnostic codes. F. Turn the isolator switch to the OFF position and remove the jumper wire.	EFLP relay	Result: A 1075-6 diagnostic code is active with the jumper installed. Install a replacement EFLP relay. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The 1075-5 diagnostic code is still active. Proceed to Test Step 5.
4. Create an Open Circuit at the Relay A. Turn the isolator switch to the OFF position. B. Disconnect the EFLP relay. C. Turn the isolator switch to the ON position. D. Use the electronic service tool to check for active diagnostic codes. Wait at least 30 seconds for activation of the diagnostic codes.	EFLP relay	Result: A 1075-6 diagnostic code was previously active. A 1075-5 diagnostic code is active with the relay disconnected. Install a replacement EFLP. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The 1075-6 diagnostic code is still active with the relay disconnected. Proceed to Test Step 5.
5. Bypass the EFLP Relay Control Wire A. Verify that the isolator switch is in the OFF position. B. Disconnect the P1 connector from the ECM. C. Disconnect the EFLP relay connector. C. Remove the wire from P1:21. D. Remove the wire from socket 2 in the EFLP relay connector. E. Fabricate a jumper wire that is long enough to reach from the ECM to the EFLP relay connector. Insert one end of the jumper into P1:21. Insert the other end of the jumper into socket 2 in the EFLP relay connector. F. Reconnect the P1 connector. Reconnect the EFLP relay connector. G. Turn the isolator switch to the ON position. Use the electronic service tool to check for an active 1075-X diagnostic code. H. Turn the isolator switch to the OFF position. Restore the original harness wiring.	Wiring	Result: There are no active 1075-X diagnostic codes at this time. Repair the faulty wiring or replace the faulty wiring between P1:21 and socket 2 on the EFLP relay connector. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 1075-X diagnostic code is still active at this time. Proceed to Test Step 6.
6. Check if a Replacement ECM Eliminates the Fault A. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming". B. Contact the Technical Communicator at a Cat dealer. Note: This consultation can greatly reduce the repair time. C. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM". D. Turn the isolator switch to the ON position. Use the electronic service tool to verify that the repair eliminates the fault.	ECM	Result: The fault is eliminated with the test ECM. Reconnect the suspect ECM. If the fault returns with the suspect ECM, permanently install the replacement ECM. Result: The fault is still present with the replacement ECM. Do not use the replacement ECM. Contact the Technical Communicator at a Caterpillar dealer.