Help i got a 01 discovery and got stuck in the mud. while trying to rock it free the m and s lights started flashing and the truck will only move in reverse. All forward gears it only revs with no movement. Reverse works fine and i didnt have any problems with transmission before this. no noises or grinding. Also the D light on the gear shift flashes and the gears 1-3 dont light up at all. Does anyone have an idea what it could be. thanks for the help

 

Sounds like a transmission fault when you were rocking in the mud.
The transmission computer may think there is a problem - whereas there is not.
Or there is a problem as maybe you lost a clutch or such.

You'll probably want to consult a ZF fault diagnostic guide for the 4HP22 - electronic

Ashcroft Transmissions - ZF4HP22

FInding a manual now is hard.
THere are a lot of spam sites coming up.

 

One thing you should know... go to any transmission shop in the winter after the first snow... rocking is a no no. If you get stuck, best to get out and physically push the car if you can a few feet forward or back and try again... or get a cable puller, rope, winch, a buddy with any of those, or a tow truck.

 

Curious... Wonder if a bad ground (coming loose due to rocking) could cause this issue. I had a few flashing M&S days with limited gears when my battery ground was partially broken off.

 

Any check engine light on if so, what fault code numbers do you have? Have you check the level and color of the ATF?

 

i do have a check engine light on but it was on prior to this. Im in the process of getting a reader since i cant get the vehicle to the auto parts store. I noticed yesterday while messing with it that the M and S lights arent always coming on but the vehicle still will not go forward. i checked the adjustment on the XYZ switch and it seems just fine. As i go through the gears the correct indication light shows on the display. i need to check the ATF today which is my next step. I was also wondering if I needed to get my battery checked. thanks for the help

 

Yes on battery. May have XYZ switch full of mud. In which case tranny computer won't know what to do. Might want to meter cable going into switch for grounds.

RAVE says :

A gear position switch on the gearbox transmits the gear selection to an Electronic Automatic Transmission (EAT) ECU, which outputs the appropriate control signals to an electro-hydraulic valve block in the gearbox.

If switch contacts don't make properly, tranny ECU will not operate valve to send fluid to make truck move forward.

 

is the gear position switch the same thing as the xyz switch? I definetly think that and checking battery are my next steps. It poring here today so it may be this weekend before i can get under there but any more info would be appreciated and i will update. thanks

 

XYZ switch tells the transmission computer and maybe the ECU too on
what gear your transmission is in via the movement of the gear selector
which you the human are free to select.

Maybe go to a self car wash and power wash the mud off the components under the rover.

 

Mud can be conductive too - to low current devices.
Best to stay out of mud if you can.