TM gear box fault

YELROM

Member
Location
North Yorkshire
We have a New Holland TM155 power command that will only drive in first gear.
It is in the field and i have not been to look at it but the lad says that no matter what gear you put it in it flashes CP for clutch pedal then when you press the clutch it changes down to first gear

Anyone any ideas what might be wrong

@cosmagedon would you have any idea?
 

Aftermaths

Member
Arable Farmer
On the right hand side, behind the bank of solenoids, you can find a pair of potentiometers that work out where everything is so it can change gear, take these off and polish up the brass where the bolt goes through (they earth through here) and also the tractor side, this usually cures any oddball tm gearbox faults. There is also a pair of sensors down there which also get bad earth's and cause issues. Usually works for me anyway
 

YELROM

Member
Location
North Yorkshire
On the right hand side, behind the bank of solenoids, you can find a pair of potentiometers that work out where everything is so it can change gear, take these off and polish up the brass where the bolt goes through (they earth through here) and also the tractor side, this usually cures any oddball tm gearbox faults. There is also a pair of sensors down there which also get bad earth's and cause issues. Usually works for me anyway
Thanks I’ll try that
 

horace

Member
Location
shropshire
There are no potentiometers on the RHS of a power command. And even if there were they definitely don't earth through the brass bushes. They are only there to prevent over torquing.
All your gearbox solenoids are under the inspection cover in the cab. Floor mat out, cover out.
I would be checking the wiring on those. Take the LHS cover off the dash by the clutch pedal. Check the wiring on the pedal potentiometer and the disconnect switch.
Check the wiring to the 3 speed sensors going into the RHS of the box. From the outside they will be mounted the same way as the damper plate sensor on the bell housing.
Are there any error codes at all?
 

cosmagedon

Member
Location
North Wales
We have a New Holland TM155 power command that will only drive in first gear.
It is in the field and i have not been to look at it but the lad says that no matter what gear you put it in it flashes CP for clutch pedal then when you press the clutch it changes down to first gear

Anyone any ideas what might be wrong

@cosmagedon would you have any idea?

First thing is to try and calibrate it, if there's a fault it will usually bring it up as a U code.
 

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