SMG200 Motor Grader Fault Case

Basic Fault Information

Item	Content
Time	2025-11-21 18:31:42
Fault Type	Electrical Fault
Equipment Serial Number	PY1120CC2082
Product Model	SMG200
Business Unit	Pumping & Hydraulics Business Unit
Product Group	23/Motor Grader
Operating Hours	2713
Shutdown Fault	No
Operation Location	Argentina
Public Element	Display
Service Order	2510014741

Fault Description

Fault of SMG200 motor grader where the clutch fails to disconnect power and there is severe shifting shock.

Fault Analysis, Troubleshooting Process and Fault Summary

Fault Analysis for SMG200 Motor Grader: Clutch Fails to Disconnect Power and Severe Shifting Shock

1. The most important prerequisite for judging this fault is to determine the cause of the clutch not being fully disengaged. Check the current of the gearbox solenoid valve and judge whether the solenoid valve is working normally. Under normal circumstances, when the clutch pedal is fully depressed, the PWM sampling value is within 8000, and the K1 current in F1 gear needs to be less than 65mA. At the same time, check whether the initial current values of the corresponding solenoid valves for F2 and F3 are consistently within 65mA. If there is a significant difference from K1 in F1 gear, it is recommended to swap the K1 solenoid valve with the solenoid valve at other positions.
2. It is confirmed that when the K1 current is greater than or equal to 65mA when the clutch pedal is fully depressed, the equipment will travel, and the sampling value will be greater than 8000 PWM. In this case, it is necessary to contact the Business Unit to provide a version of the controller program, and the current of the solenoid valve is adjusted through the program.
3. Before flashing the program, it is necessary to feedback the program version number in advance. If the program version number before the update is the same as the version number after the update, the program flashing will be unsuccessful. As shown in the figure: 6.92

Summary

This fault case involves the SMG200 motor grader, with the main fault being that the clutch cannot disconnect power and there is severe shifting shock. The troubleshooting focuses on the clutch disengagement status and the working condition of the gearbox solenoid valve. First, it is necessary to check the solenoid valve current and PWM sampling value: when the clutch pedal is fully depressed, the K1 current in F1 gear should be less than 65mA, and the PWM sampling value should be within 8000; if the initial current of each solenoid valve is inconsistent, solenoid valve replacement is recommended. If the K1 current is ≥65mA and the PWM value exceeds 8000 when the clutch is fully depressed, the Business Unit needs to provide a controller program to adjust the solenoid valve current. It should be noted that the program flashing will fail if the version number before and after the update is the same. This case reminds that the detection of solenoid valve current and program version confirmation are key links in troubleshooting such electrical faults.