I have to replace the unit on my 03 Avalanche. It started shifting into 4 low by itself in parking lots and will not stay in 2 high when shut off. The service 4wd is displayed on the dash about 50% of the time.
Is a cheap Amazon sourced unit going to last more than a few months?
Is there anything else to do while I am down there?
Is there any reason to not just swap the encoder ring instead of the whole motor unit? IE does the factory motor usually outlast the ring sensor?
This stupid truck was ready to sell, freshly detailed and then this happened. 
The encoders usually die because corrosion on the transfer case's case warps or cracks it. A good carbide scraper makes short work of it.
The 4wd in my Silverado got confused and wouldn't shift out of 4wd. I pulled the 4wd fuse for a couple if minutes and it reset itself. It has been fine every since.
In reply to Trent (Generally supportive dude) :
when I traded in my 05 i cleared the codes when i got to the dealer and thankfully they didn't pop up on their test drive
If I were trading it in I would just clear the codes. I somehow feel a bit shady doing so for a private sale.
Corrosion like that isn't an issue in the PNW.
It is most likely the encoder since the dash thinks it is in neutral as I am cruising down the road. If I try to select a gear it will sometimes do so with an audible clunk, other times it will do nothing or the light will change on the buttons with no sound coming from the T-case.
I think I'm gonna just get a hundred dollar amazon unit and see if it lasts long enough to sell it.
$109 Amazon encoder motor and 45 minutes later and I apparently have 2wd for the first time in my ownership of this thing. It is a totally different truck now. I had just assumed that the "auto 4wd" mode it was stuck in was 2wd until things got loose. Nope. It drives so much nicer now.
I'm curious what this will do to the fuel economy but I hope to not own it long enough to find out.
Now if someone would remake the encoder ring for the Quadra steer.
