88456A 3 Mercruiser HARNESS ASSEMBLY, AUTO TRIM

Table 1
Diagnostic Codes for the EPP 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 a low current condition in the EPP relay circuit.
The warning light will come on. The diagnostic code will be logged.
The ECM is unable to activate the relay for the EPP. The EPP will not operate or the EPP 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 a high current condition in the EPP relay circuit.
There is a high current condition in the EPP 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 EPP. The EPP will not operate or the EPP will operate all the time. The engine will not operate. The following background information is related to this procedure:The EPP is used to provide positive fuel pressure to the high-pressure fuel pump. When the keyswitch is turned to the ON position, the ECM will activate the EPP. If the engine is not running, the ECM will deactivate the EPP after 2 minutes.Not all engines are equipped with an EPP. Ensure that the ECM parameters for the EPP are correctly configured for the hardware equipped.
Illustration 1 g06366341
Schematic for the Electric Priming Pump (EPP) relay
During the following procedure, refer to the electrical schematic for the application.Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Turn the keyswitch to the OFF position.
B. Check the fuses.
C. Thoroughly inspect the connectors between the EPP relay and the engine ECM. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
D. Check the harness and wiring for abrasion and for pinch points from the EPP to the ECM and from the EPP relay to the battery.
Note: Do not disconnect the ECM connector at this stage. The ECM can only be disconnected and reconnected 10 times before damage to the harness connector may occur.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring. A fuse is blown.
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. Replace blown fuses.
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.
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. Do not start the engine.
C. Make a note of any active diagnostic codes.
D. Wait for at least 2 minutes for the Electric Fuel Lift Pump (EPP) to deactivate. Make a note of any active diagnostic codes.
Diagnostic codes
Result: Diagnostic code 1075-5 is active or recently logged.
Proceed to Test Step 3.
Result: Diagnostic code 1075-6 is active or recently logged.
Proceed to Test Step 5.
3. Create a Short Circuit at the EPP Relay
A. Turn the keyswitch to the OFF position.
B. Disconnect the harness connector for the EPP relay.
C. Fabricate a jumper wire that is 150 mm (6 inch) long.
D. Use the jumper wire to connect Test Point 1 to Test Point 2 on the harness connector for the EPP relay. Refer to Illustration 1.
E. Turn the keyswitch to the ON position. Do not start the engine.
F. Use the electronic service tool to check for an active 1075-6 diagnostic code.
G. Wait for at least 2 minutes for the EPP to deactivate. Check for an active 1075-5 diagnostic code.
H. Turn the keyswitch to the OFF position.
I. Remove the jumper. Leave the connector for the EPP disconnected.
Open circuit
Result: A 1075-6 diagnostic code was active with the jumper installed.
Repair: Install a replacement EPP relay.
Reconnect the connector for the EPP relay.
Turn the keyswitch to the ON position. Do not start the engine. Check for active diagnostic codes.
Wait for at least 2 minutes for the EPP to deactivate. Check for active diagnostic codes.
Confirm that the fault has been eliminated.
Result: A 1075-5 diagnostic code is still active with the jumper installed. There is a fault in the wiring or