7778A 3 Mercury SWITCH BOX

Probable Causes
Engine operation
Diagnostic codes, event codes and derates
Fuel quality
Fuel injection
Engine speed/timing
Air inlet and exhaust system
Check for damaged accessory equipmentRecommended Actions
Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Engine Operation
Use Cat® Electronic Technician (ET) to check the "Current Totals" for excessive idle time and/or for a high load factor. Excessive idle time and/or for a high load factor would be indicative of poor operating habits.
Operation
Result: Excessive idling is indicated.
Repair: Make the necessary changes. Ensure that the problem is resolved.
Result: Excessive idling is not indicated.
Proceed to Test Step 2. Note: Fuel consumption may also be affected by environmental conditions such as wind and snow.
Table 2
Troubleshooting Test Steps Values Results
2. Diagnostic Codes, Event Codes and Derates
Certain diagnostic codes and/or event codes may cause poor performance.
A. Connect Cat ET and download the "Warranty Report" from the engine Electronic Control Module (ECM) before performing any troubleshooting or clearing diagnostic trouble codes.
B. Wait at least 30 seconds in order for any codes to become active.
Codes and Derates
Result: Codes are active.
Repair: Troubleshoot the codes that are present.
Proceed to Test Step 3.
Result: No codes are active.
Proceed to Test Step 3.
Note: Certain failure modes of a sensor may produce an output signal that does not represent an accurate measurement. The inaccurate measurement can occur when the signal is in the operational range of the sensor. Use Cat ET to check that the pressures and the temperatures are fluctuating normally. Also check that the values are reasonable for the conditions that are present.
Table 3
Troubleshooting Test Steps Values Results
3. Fuel Quality
A. Check fuel quality.
Cold weather adversely affects the characteristics of the fuel.
Poor Fuel Quality
Result: Fuel quality is undesirable.
Repair: Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation. Ensure that the problem is resolved.
Result Fuel quality is desirable.
Proceed to Test Step 4.
Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
Table 4
Troubleshooting Test Steps Values Results
4. Fuel Injection
A. Perform the "Fuel System Verification Test" in Cat ET. Refer to Troubleshooting, "Injector Solenoid - Test".
Fuel Injection
Result The "Fuel System Verification Test" failed.
Repair: Diagnose the problem and then repair the problem. Clear all logged diagnostic codes. Verify that the repair eliminated the problem.
Result The "Fuel System Verification Test" completed successfully.
Proceed to Test Step 5.
5. Engine Speed/Timing
A. Perform a speed/timing sensor calibration. Refer to the calibration procedure Troubleshooting, "Timing - Calibrate".
Engine Speed/Timing
Result The speed/timing sensor calibration failed.
Repair: Resolve the issue. Ensure that the problem is resolved.
Result The speed/timing sensor calibration completed successfully.
Proceed to Test Step 6.
6. Air Inlet and Exhaust System
A. Inspect the air filter for a restriction. If the air filter shows signs of plugging, clean the air filter or replace the air filter.
B. Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to Systems Operation/Testing and Adjusting.
C. Check the turbocharger and exhaust balance valve. Refer to Troubleshooting, "Exhaust Balance Valve - Test".
Air inlet and Exhaust System
Result The air inlet and exhaust system is not functioning correctly.
Repair: Make the proper repairs. Ensure that the problem is resolved.
Result The air inlet and exhaust system is functioning correctly.
Proceed to Test Step 7.
7. Check for Damaged Accessory Equipment
A. Check all accessory equipment for problems that may create excessive load on the engine.
Damaged Accessory Equipment
Result Problems have been found with the accessory equipment.
Repair: Repair any damaged components or replace any damaged components.
Result No problems have been found with the accessory equipment.