What happens when Transfer case encoder motor breaks?

[Sickboy73]

I have an '04 Yukon XL 2500 with the 8.1L (gasoline not diesel) Vortec. About 2 weeks ago it automatically engaged into 4wd low at take off and while rolling I lost all my gears, it would not go into Drive or Reverse and when I put it into park it was like I put it into Neutral and it made some sort of grinding noise. At that time the Check Engine light came on. I got the code which is P2771.I tried switching it back to 2wd but no luck. I looked up the code and it sounds like it could be several different things anyone know what broke, could it be the transfer case or maybe the transmission? Please help.

[VikingTrad3r]

Hi.

 

The only time i have seen a front diff go out is on my dads blazer. i know, probably different.

 

However all that would happen for him is htat he would put it into 4wd and it just wouldn't go.

 

when we pulled the electric engagement motor out off the front diff, it was just old and seized up inside. with broken bits as it was trying to engage but some forks broke off or something.

 

we replaced it and it works great now. part was cheap like $50.

 

but when you say the encoder, i am thinking maybe you are not meaning the little electric motor down at the diff that moves the forks to cause the front diff to be engaged.

 

if you are hearing grinding, i would be inclined to check the transfer case, or, the front diff. i would start with the transfer case.

 

one thing i did a long time ago before i replaced the front diff on my 06 denali, was i took it to a shop where they raised it up on the 4post lift with these little rollers for the tires. they drove the car in place and underneath the car we could use a long broomstick handle to see the noise was comeing from the front diff. i paid them $100 for 1 hour and then i did the repair myself after it was diagnosed. They wanted $2000 and I did it for $250 parts and a full saturday and full sunday at home.

[davester]

It's unlikely to be the front diff, as if it is either wedged so it doesn't turn or spins freely, the truck would feel like it wants to move or would move. And there's no sensor on the front diff that tells you if it's working or not, only if the actuator is engaged or not.

 

There's probably something wrong with the transfer case.