SHAFT 3W0602 - Caterpillar

Probable Causes
Excessive load
Brakes
Programmable parameters
Vehicle speed circuit
A system on the power train data link
Electronic control system
Accelerator pedal position sensor
Air inlet and exhaust system
Fuel systemRecommended Repairs
Verify that the Load is Not Excessive
Interview the operator. Verify that the load is within the specification of the engine and the drive train.Check the Brakes
A brake that drags can limit the vehicle's speed. Check the vehicle's brake system for proper operation.Check Programmable Parameters
Certain programmable parameters may limit vehicle speed. Use the Caterpillar Electronic Technician (ET) to check the following programmable parameters:
Vehicle Speed Limit (VSL)
Lower Gears Engine RPM Limit
Intermediate Gears Engine RPM Limit
Gear Down Protection Engine RPM Limit
VSL Protection
"PTO Top Engine Limit" with the PTO on/off switch in the ON position
"Maximum PTO Vehicle Speed" with the PTO on/off switch in the ON position
Soft Vehicle Speed LimitSet each parameter to the maximum value one at a time and determine whether the problem is corrected.Note: Programming the "Soft Vehicle Speed Limit" to "No" may eliminate the complaint.Check the Vehicle Speed Circuit
Use Cat ET to monitor the vehicle speed signal while the vehicle is operated. Verify that the vehicle speed signal is reasonably close to the vehicle's actual speed. Refer to Troubleshooting, "Vehicle Speed Circuit - Calibrate", if necessary.Check the Electronic Control System
Use Cat ET to monitor the fuel position, the rated fuel limit, and the FRC limit. While the vehicle is operating under full load, the parameters should meet the following conditions:
The fuel position is equal to the rated fuel limit.
The fuel position is less than the FRC limit.If the fuel position is equal to the rated fuel limit and the fuel position is less than the FRC limit, the electronic control system is operating correctly.If the fuel position is not equal to the rated fuel limit and/or the fuel position is not less than the FRC limit, check the boost pressure on Cat ET when the engine is not running. The boost pressure should be 0 kPa (0 psi).Check the Accelerator Pedal Position Sensor
Use Cat ET to monitor the status of the accelerator pedal position sensor. Operate the engine at high idle with the vehicle in neutral. If the engine cannot reach the programmed "Top Engine Limit", check the duty cycle for the accelerator pedal position sensor. Refer to Troubleshooting, "Accelerator Pedal (Throttle) Position Sensor Circuit - Test".Check the Systems on the Power Train Data Link
A system that is connected to the power train data link may be limiting the vehicle's speed. These systems include the brakes and the transmission.Note: You may need a special service tool in order to monitor the other modules on the J1939 data link. Obtain the necessary equipment, when possible. Monitor the appropriate parameters while the vehicle is experiencing problems. Determine if the systems are limiting the engine's speed.Determine if the condition is normal operation. Refer to the vehicle's Original Equipment Manufacturer (OEM) if the condition is not normal operation.Check the Air Inlet and Exhaust System
Check the air cleaner element according to the procedure in the Operation and Maintenance Manual.Check the