6420 deere 4 wheel drive

[Dale2]

I have a 6420 coming into the shop. The 4 wheel drive is staying engaged all of the time. Can anyone point me in the direction and tell me how to test this.
Thanks
Dale

 

[WTW]

Dale, First thing to know / understand is: The MFWD clutch is mechanical / spring engaged and Hydraulic released. When ever the tractor is shut OFF / setting the MFWD clutch is engaged. When tractor is running and MFWD switch is OFF to disengage the MFWD, power to clutch control solenoid is turned ON. So if MFWD is ON all the time, problem may be that there no voltage to control valve to turn it OFF, which in turn opens control valve to apply hydraulic clutch pressure to release the clutch / shut it OFF. Might be just an open circuit to MFWD clutch control solenoid valve. DW

 

[620 John]

(quoted from post at 15:49:47 12/18/23) I have a 6420 coming into the shop. The 4 wheel drive is staying engaged all of the time. Can anyone point me in the direction and tell me how to test this.
Thanks



Another thing to add is if you have to fix any wires going to that solenoid make sure you hook them up the same way they are. I saw someone run new wires to the MFWD solenoid on a 7810 and had them backwards. Don't remember if it fried the solenoid or if it just didn't work because polarity mattered in that case. Some solenoids like these are polarity sensitive and some aren't.

If it's not electrical then hook up a lube pressure gauge to transmission and watch lube pressure while turning MFWD on an off. Lube pressure will drop slightly when turned OFF because it's applying oil pressure to disengage the clutch. If the lube pressure drops off to zero or no pressure then there's an internal leak possibly with clutch shaft sealing rings, clutch piston, or solenoid o-rings.



This post was edited by 620 John on 12/18/2023 at 04:04 pm.

 

[Tech 7]

Just a guess from a distance but check the brake pedal switches. If one of them is remaining closed it can activate the MFWD I believe.

 

[islandgreen]

Maybee poor conection or broken wire on celenoid,as was already said this clutch is powered to release clutch.