SHAFT 9M4789 - Caterpillar

Probable Causes
Excessive load
Programmable parameters
Cold mode operation
Malfunctioning cylinder
Power train data link
Flash file
Torque limiting featureRecommended Actions
Check the Load
Verify that the load is not excessive for the engine's rating.Check the Programmable Parameters
Use the Caterpillar Electronic Technician (ET) to check the status of the following parameters:
Lower Gears Engine RPM Limit
Intermediate Gears Engine RPM Limit
Gear Down Protection Engine RPM LimitSet each parameter to the maximum value one at a time and determine whether the problem is corrected.Check for Cold Mode Operation
Use Cat ET to verify that the engine is not in cold mode. Cold mode is indicated in the upper corner of any status screen.Check for a Malfunctioning Cylinder
Check the electrical connectors for the unit injectors and the Engine Control Module (ECM). Look for corrosion and for moisture.Use Cat ET to perform the cylinder cutout test. Disable each cylinder with the test. Disabling each cylinder can identify a malfunctioning cylinder.If a malfunctioning cylinder is identified, refer to Troubleshooting, "Injector Solenoid Circuit - Test".Check the Power Train Data Link
Use Cat ET to check the "Power Train Data Link". Monitor the parameter while the vehicle is experiencing problems. Determine if the SAE J1922 power train data link or the SAE J1939 power train data link is limiting the engine's power.Determine if the condition is normal operation. Refer to the vehicle's Original Equipment Manufacturer (OEM) for repairs if the condition is not normal operation.Check the Flash File
Verify that the correct flash file is installed. Refer to Troubleshooting, "ECM Memory - Test".Check the Torque Limiting Feature
Verify that the "Torque Limit" configuration parameter is programmed correctly for the application.Verify that the torque limit switch is Off.Cat ET does not indicate the status of the torque limit switch. Check the vehicle's response with the torque limit switch Off. If the torque limit switch is Off and you suspect that the ECM is limiting the engine's power, check the circuit for the torque limit switch. Refer to Troubleshooting, "PTO Switch Circuit - Test".