First post today, I have been in stealth mode for a while and have picked up a lot of great tips. I have a problem with the automatic transmission; symptoms are: stays in first gear until approximately 2700 rpms and then does a hard shift into third gear, quickly followed by the flashing M and S lamps (limp mode). Shutting off the truck and restarting cancels the lamps and all appears normal. Before it shifts out of first, I can select 1 through D and see the selector changes on the instrument panel. I have noticed that while coasting in first gear going downhill, the truck will accelerate without the engine rpm rising. I also have noticed that if I deliberately select first gear, it will still shift out of first into limp mode.

I have a P0722 code, so I drained the transmission fluid and replaced the output shaft speed sensor and refilled the transmission with new fluid. The old fluid was somewhat dirty, but no metal. I have seen worse. I have replaced the alternator voltage regulator and the battery, and I'm seeing 14.1 volts output. I still have the P0722 code. I'm wondering if I have a bad transmission control unit? I realize that if it is bad and I get a used one, I will need the body control unit from the same vehicle.

Any thoughts on the failure mode of these transmissions?

Thanks!

 

have you looked up the xyz switch in the RAVE?

 

I've read several threads about the xyz switch, including how to rig it in the RAVE. The symptoms don't seem to fit what is happening with my transmission, but what the heck, I can take it apart and clean it. The dealer told the former owner that the transmission needed replaced, but it certainly seems like an electrical glitch to me.

Thanks for the input.

 

The description for P0722 is "Torque converter slipping." Why would the XYZ or any other electrical component be suspect for that code? Why wouldn't you try to further diagnose the torque converter or just replace it?

 

Came here for this.
To the OP, no trans flush in the world is gonna help your problem. And if it was the control unit, this wouldn't be your issue. Yea it sucks to pull a trans, but you could either cry or keep drinking...

 

I happen to have a neighbor with a 2000 Disco II that has an engine that is overheating. Driving his (briefly) feels the same as mine with the bad tranny, i.e. no hesitation, no slipping in drive or reverse. I'm not saying the transmission isn't bad per the code, but it doesn't feel bad. I bought this hoping I could fix it, but this along with the frame rust is going to make this go down the road.

Thanks everyone for your replies. Maybe an LR 3 in my future.

 

Another option instead of a brand new trans, would be a used trans with lesser miles and a new torque converter.

also, its not the trans, its the torque converter, but if you are pulling the trans, might as well replace it. Good luck to whatever you choose to do.