878175 Mercury LINK ASSEMBLY

Probable Causes
Active codes and logged codes
Fuel system
Fuel injectors
Machine hydraulics causing excessive loadRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Active Codes and Logged Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM) . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Determine if a code is active or logged.
Diagnostic code
Result: A code is active or logged.
Troubleshoot any active codes before continuing with this procedure.
Result: A code is not active or logged.
Proceed to Test Step 2.
2. Check the Fuel System
Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Inspect the fuel system for external leaks.
D. Check that there are no external leaks, no air in the clear primary fuel filter. Change the primary fuel filter and the in-line filter for the fuel transfer pump.
E. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, "Fuel Quality - Test" for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.
F. Check for the proper operation of the fuel transfer pump. Replace the pre-filter if excessive contamination or if the maintenance interval is exceeded. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for test information.
Fuel system
Result: The fuel system is OK.
Proceed to Test Step 3.
Result: The fuel system is not OK.
Make the necessary repairs.
3. Fuel Injectors
A. If service has been performed on the engine fuel system recently, verify that the injector trim codes in the Engine ECM match the injector for each cylinder. If injectors were moved between cylinders or if an injector was replaced and the injector trim codes were not updated in the Engine ECM, this can cause an engine miss.
A. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu. Cut out each cylinder one at a time to listen for improvements in the engine. If engine sound improves while cutting out a specific cylinder or cylinders, then check that the injector(s) are working properly by using 440-6907 Injector Kit.
Note: The injector deliver quantity is not a reliable indicator of a failed injector. It is not recommended to use that test in determining if an injector is failed.
Fuel Injectors
Result: If injector(s) trim codes for each cylinder do not match what is in the Engine ECM, then refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and on-line. Confirm that this resolves the issue.
Result: If injector(s) are found to be defective, then replace the injector(s). Refer to Disassembly and Assembly, Electronic Unit Injector - Remove and Install. Refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and online. Confirm that this resolves the issue. Note: If two or more injectors are not working properly, this is likely a result of water in the fuel, bad fuel, or contaminated fuel. Contaminated fuel can occur by pre-filling the fuel filter or contamination during a previous repair of the fuel system. The root cause needsto be determinedto prevent a repeat occurrence.
Result: There are no previous known services on fuel system and there was no noticeable improvement during the cylinder cut out test. The customer could have ordered injectors through parts and did not change the injector trim codes in the Engine ECM. Visually confirm that the injector trim code for each cylinder matches what is in the Engine ECM. Refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and on-line.
4. Machine Hydraulics Causing Excessive Load
Refer to the machine System Operation/Testing and Adjustmanual to ensure that machine hydraulics are working properly.
Machine Hydraulics
Result: Machine hydraulics are causing an excessive load.
Make the necessary repairs.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).