5030800 JOHNSON CAP, Connector

Probable Causes
Diagnostic Codes and Events
Starting Aids
Active Engine Derate
Decelerator Pedal
Throttle Switch
Turbocharger outlet pressure sensor (intake manifold air), Rated fuel position and/or FRC fuel position
Fuel supply
Air inlet and exhaust system
Accessory equipmentRecommended Actions
Diagnostic Codes and Events
Certain diagnostic codes and/or event codes may cause poor performance. Connect Caterpillar Electronic Technician (Cat ET) and check for active codes and/or logged codes. Troubleshoot any codes that are present before continuing with this procedure.Starting Aids
Air Inlet Heater (If Equipped)
Make sure that the air inlet heater is programmed to On position. For additional information on the air inlet heater, refer to Troubleshooting, "Air Inlet Heater Circuit-Test".Ether Injection System (If Equipped)
Make sure that the ether injection system is programmed to the ON position. For additional information, refer to Troubleshooting, "Ether Injection System-Test".Oil Grade Plugs (If Equipped)
Make sure that the "Oil Grade" is programmed correctly. The identification of the oil grade in the engine may be viewed on the second Cat ET status screen. For additional information on the plugs for the oil grade detection, refer to the Operation and Maintenance Manual, "Engine Oil and Filter - Change".Active Engine Derates
If an active derate occurs, the warning lamp will flash. "Engine Derate" will appear in the box for engine status on any Cat ET status screen. Verify that the set points for "Derate" that are in the Programmable Monitoring System have been programmed to the values that are correct. An FMI code will appear for an active derate on Cat ET status screens.Decelerator Pedal
Monitor the decelerator pedal on Cat ET. Verify that the decelerator pedal is operating properly. Refer to Troubleshooting, "Throttle Position Sensor Circuit-Test" for the proper troubleshooting procedure.Throttle Switch
Monitor the switch signal on Cat ET. Verify that the signal is stable at the low idle position. Verify that the signal is stable at the high idle position. Move the switch from the low idle position to the high idle position in order to verify that the engine is able to reach the high idle position. Refer to Troubleshooting, "Throttle Switch Circuit-Test" for the proper troubleshooting procedure.Turbocharger outlet pressure sensor (intake manifold air), Rated fuel position and/or FRC fuel position
Monitor "Fuel Position" and "Rated Fuel Limit" on the fourth Cat ET status screen. If "Fuel Position" does not equal "Rated Fuel Limit" then check air inlet manifold pressure.
Verify that there are no active diagnostic codes that are associated with the Turbocharger Outlet Pressure Sensor (intake manifold air) or the Atmospheric Pressure Sensor.
Monitor turbocharger outlet pressure on the second Cat ET status screen and Atmospheric Pressure for normal operation. Note: Atmospheric Pressure is not a default parameter on an Cat ET status screen. A new parameter screen must be set up in order to monitor the Atmospheric Pressure sensor.Fuel Supply
Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
Check the fuel tank for foreign objects which may block the fuel supply.
Check for air in the low pressure fuel supply system if any of the following procedures have been performed:
Replacement of the fuel filters
Service on the low pressure fuel supply circuit
Replacement of unit injectors
Purge air from the low pressure fuel supply circuit. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the correct procedure.Note: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.
Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Instruction, SEBD0717, "Diesel Fuels And Your Engine".
Check the fuel pressure during engine cranking. Check the fuel pressure on the outlet side of the fuel filter. Refer to Specifications for correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve.Air Inlet and Exhaust System
Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.
Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System".Accessory Equipment
Check all accessory equipment for problems that may create excessive load on the engine. Repair any damaged components or replace any damaged components.