Trannie Brain Teaser

[Norseman]

Ok, a friend of mine is experiencing this:

 

2005 Silverado Z71

 

While driving the truck appears to drop into neutral and send no power to the wheels, but if he switches into 4H and then back to 2H the truck will again drive. He also noted that felt like the truck did not want to shift into 4L.

 

This is beyond my capabilities so I told him there were a bunch of bright guys here and I'd ask y'all.

 

Anyone else experience this or have any ideas?

 

 

Thanks

[Nytemare]

My bet is on 4wd encoder motor. Its actually the T-case thats going into neutral...not the trans.

[Draenor]

 

 

My bet is on 4wd encoder motor. Its actually the T-case thats going into neutral...not the trans.

+1

[Norseman]

Thanks for the replies guys.

 

The Trannie has 170k miles on it and it is serviced regularly. The problem occurs randomly (does not matter what speed) but will start working again every time he switches to 4H and back to 2H.

 

The x-fer case encoder motor theory makes alot of sense. Is there anyway a DIY'er can test these?

[Nytemare]

Thanks for the replies guys.

 

The Trannie has 170k miles on it and it is serviced regularly. The problem occurs randomly (does not matter what speed) but will start working again every time he switches to 4H and back to 2H.

 

The x-fer case encoder motor theory makes alot of sense. Is there anyway a DIY'er can test these?

Other than get another encoder and swap it out and try....unfortunately no...the motor is working...but it sounds like there is something wrong thats allowing it to fall into neutral. Spring related...bushing worn...getting a stray voltage signal...

 

Try unplugging the encoder and see if it stays in 2wd...you'll probably get a service light, and a service 4wd system msg, but you can test the theory..it should only stay in 2wd with the encoder unplugged.

[Norseman]

Thanks for the replies guys.

 

The Trannie has 170k miles on it and it is serviced regularly. The problem occurs randomly (does not matter what speed) but will start working again every time he switches to 4H and back to 2H.

 

The x-fer case encoder motor theory makes alot of sense. Is there anyway a DIY'er can test these?

Other than get another encoder and swap it out and try....unfortunately no...the motor is working...but it sounds like there is something wrong thats allowing it to fall into neutral. Spring related...bushing worn...getting a stray voltage signal...

 

Try unplugging the encoder and see if it stays in 2wd...you'll probably get a service light, and a service 4wd system msg, but you can test the theory..it should only stay in 2wd with the encoder unplugged.

 

 

That's a good idea! I'll have him try that.

 

Thanks

[Nytemare]

Yup...they aint cheap...especially for something that craps out fairly often.

[Norseman]

D@mn!!!! Those X-fer case encoder motors are expensive! I sure am glad mine is the manual type.

[jf781]

How many miles are on it? When was the last tranny service?

 

Speed it happens at, does it do it all the time or just on occasion? If it drives in 4H (if it consistently happens) will it do it as well?