HARNESS AS-CAB 1993334 - Caterpillar

Probable Causes
Engine derate or active codes
Cold mode
Flash file
Throttle signal
Electrical connectors
Unit injectors
Intake manifold pressure
Air inlet and exhaust system
Fuel supplyRecommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.Engine Derate or Active Codes
Some engine monitoring parameters that are capable of triggering an engine derate do not produce an event code. Connect Caterpillar Electronic Technician (ET) in order to check for a derate of the engine.Certain diagnostic codes and/or event codes may cause poor performance. Use Cat ET to check for active codes and for logged codes. Troubleshoot any codes that are present before continuing with this procedure.Note: Although a sensor's signal may be in the operational range of the sensor, the signal may not represent the actual reading. Use Cat ET to check that the pressures and the temperatures are fluctuating. Also check that the values are reasonable for the conditions that are present.Cold Mode
Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may slow throttle response.Flash File
Verify that the latest flash file is installed in the Electronic Control Module (ECM).Throttle Signal
Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed. Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for information that is related to testing the system.Electrical Connectors
Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the J300/P300 connectors for the unit injectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".Unit Injectors
Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
Perform the "Cylinder Cutout Test" on Cat ET in order to determine the performance of each cylinder. Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for the proper procedure.Intake Manifold Pressure
Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should reflect the information below.
Table 1
"Fuel Position" = "Rated Fuel Limit"    
and    
"Fuel Position" < "FRC Fuel Limit"    If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating correctly. Otherwise, proceed with the next Step.
Monitor the status of the "Boost Pressure" parameter and the "Atmospheric Pressure" parameter on Cat ET. When the engine is not running, the correct value for the intake manifold pressure sensor is 0 kPa (0 psi).Air Inlet and Exhaust System
Observe the check engine lamp. Check for an air filter restriction indicator. 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 Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System".Fuel Supply
Visually check the