new holland TD75da 4wd does not disengage properly

[rackmaster2]

4wd does not disengage when rocker switch is turned back to 2wd.
But it will eventually go back to 2wd usually takes several minutes.
4wd light does come on when you brake.
when you tun engine off and crank back up, then it will be back in 4wd again. even when you were in 2wd when you shut down
not that big of issue but do not want it to be in 4wd when on blacktop, so it needs to work properly .
so , point me in right direction, rocker panel switch? solenoid ?

also, best places to get an operators manual for it?

 

[Agvg]

Sounds normal, it uses the 4WD as front brake so its by design it engages when you brake.

 

[Agvg]

And it will be in 4WD when the engine is stopped, it uses oil pressure to disengage 4WD, should not use long time to enter 2WD.

 

[RickB]

Is 4WD remaining engaged with the rocker in 2WD or is it that the dash icon stays lit and the tractor is shifting to 2WD?
Could be a bad pressure switch and the drive is functioning properly.

 

[rackmaster2]

Yes, I know that the 4wd icon comes on when breaking ,I just wanted all to know that was acting correct.

 

[rackmaster2]

And it will be in 4WD when the engine is stopped, it uses oil pressure to disengage 4WD, should not use long time to enter 2WD.

My others do not do this , if Switch and dash icon in 2wd when engine stopped , when I restart they are still in 2wd.

This one will be in 4wd after restarting engine

 

[rackmaster2]

Is 4WD remaining engaged with the rocker in 2WD or is it that the dash icon stays lit and the tractor is shifting to 2WD?
Could be a bad pressure switch and the drive is functioning properly.

Both, dash icon shows 4wd and it is in 4wd after several minutes of putting rocker switch in 2 wd.
Takes 10 to 20 min for it to disengage to 2wd
But it eventually does

 

[Agvg]

But it reacts instantly when you brakes?

 

[Agvg]

Take a multimeter an measure if the switch hangs, or is it a simple on/off you could try a another switch.

 

[LouNY]

Many of the farm tractors use hydraulics to disengage the front axle drive clutches.
To engage the front drive a solenoid dumps the hydraulic pressure off the clutch pack,
which lets the multi-disk wet clutch put the power to the front wheels.
Many of them when both brake pedals are applied ( some above a certain speed) will automatically engage the 4 wd to provide 4 wheel braking.
If you unlock your pedals and apply just one brake you most likely will not see the 4wd engage light.
If yours is taking so long to disengage I would believe that you have a restriction in the porting going to the solenoid actuator or a leak in the internal system.
It is also designed to engage when the engine is off.