I had a diagnosis of a failed transfer case encoder motor. This was in response to no lights at the switch and no reaction from the TC encoder motor also the scanner was unable to communicate with it.

So now that winter is here I have an encoder motor but have been dealing with a failed fuel pump and leaking lines. I replaced the vacuum switch at the TC and refilled the TC. I noticed the vacuum lines had fluid in them. Now I have 4x4 back but here's the question I wouldn't have expected this too fix the problem so does make sense?

If so please explain it to me.

 

The only thing I can think, is your switch gave out completely...

 

Doesn't make sense unless you replaced the ATC fuse in the underhood relay center or repaired poor connection at the TCCM at the same time that you fixed the Transfer case vacuum switch. p.s. scanner does not communicate with 3-button TCCM, only the 4-button.

 

The vacuum switch on the transfer case has a history of leaking fluid up into the vacuum lines. Installing the new type of switch from GM and replacing or blowing out the lines is most likely necessary.