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Military 850JR mistrack at high speed

USMCDOZER29

New Member
Joined
Feb 4, 2026
Messages
1
Location
29 palms
I have a military 850JR dozer Product ID #T0850JR178529 that will not complete calibration for tcu due to it mistracking on the right side at high speeds causing the dozer to go in circles. Everything runs smoothly at lower speeds, no mistrack, previous employee who worked here ordered two transmission pumps thinking that was the issue, after I replaced both pumps still had the same issue. No grinding coming from final drives or metal in the oil. It keeps throwing a code for right motor solenoid short circuit, all harnesses have been previously replaced and all in tact, only one that hasn't been is the tremble harness, which may be an issue. Also just replaced motor solenoid still same issue. I'm wondering if anyone else has had this issue and whether it could be the motor or even the speed sensor.
 

Tones

Senior Member
Joined
Mar 15, 2009
Messages
4,187
Location
Ubique
Occupation
Ex land clearing contractor, part-time retired
Check the speed actuator in the hydraulic motor, could be as simple as a weak or broken spring in there. Usually the actuator runs zero pressure in low speed then requires pressure to change the swash plate angle for faster speeds.
 

fast_st

Senior Member
Joined
Dec 1, 2010
Messages
1,619
Location
Mass
Occupation
IT systems admin
I was thinking disable 'Tokyo Drift' mode but a short somewhere. Does the error pop up constantly? If you have a plug pinout you could disconnect the harness mid-point and check the resistance values in both directions to isolate part of the harness and the right side motor solenoid.
 
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