Awesome post.


That needs to be stickied somewhere.

 

Bill, What years does that apply for? I'm thinkin' anything '95+, but just want to be sure. I've prepared a post to put into the DIY section with this information and I just want to make sure everything is correct.

 

Your right that is an awsome post. I haven't had time to do any more checks in the last day but as a note to lastcoupe, before I changed the vacum hose's the other day it would sometimes shift no problem and sometimes with a clunk, it always shifted back to 2hi with no problem. Now since I changed the hoses it won't shift at all, then no buttons work. I haven't unhooked the battery since this happened the last time so I will try and read the codes. Is it a big deal to change the vacum switch, it that switch were i unplugged the three vacum lines from. I unplugged it and put the new lines on then plugged it back in to whatever is on top the the t-case.
I will post back ASAP
thanks

 

HANR......thanks..I try.

Kyle it is for all OBD 2 vehicles (the OBD1 trucks don't have 13 pins in the DLC) 1996+ and probably some of the late 1995, but I can't be sure of that. BUT this does not apply to vehicles equipped with an automatic t-case(RPO NP8 with the 4-button switch) they are class 2 communication devices (you need a tech 2 or other scan tool to retrieve their codes). Only the electronically shifted non-automatic (RPO NP1) transfer case control modules can be checked this way.

Scott the switch is very easy to replace..(keep in mind that I say that having full access to an automotive lift......I've never tried it on my back...lol) yes it's the one on the t-case with a 3 hose manifold connected to it...MAKE SURE YOU HAVE THE MANIFOLD ORIENTED CORRECTLY when you plug it back in, there is a tab that sticks out of the switch that goes into a hole on the manifold to make sure it is on right. Use a 3/4" open end wrench to break it loose and it will spin off by hand.....Iput together an estimate for one this week at work and it cost $45.00 from our parts department. IF you or anyone else wants to buy one of these I can get them at my cost of $18.00 plus shipping.

 

Thanks Bill. I remembered something about the Auto & AWD control modules being class 2, but couldn't remember it exactly.

I'll get this into the DIY section right away!

 

Your welcome.

And yes, you can do this on your back.
Lift sure make life easier, however you can live without them. you can even drop the tranny without lifting the truck off the ground. One thing for sure, wear your eye gear.

 

Lastcoupe - Here is the lastest update.

First - having read your last post, I may not have the vacum lines plugged into the manifold right, I never noticed a line up hole. I will have to double check that tomorrow.

Second - Yesterday I read the codes as per your instructions andit had dropped the code 2. Encoder motor. This code was stored after I replaced the vacum lines and tryed to shift (I had the battery out when I replaced the lines so I would assume that this cleared any previous codes)so I am wondering if I have the vacum connection on wrong if that might be screwing the encoder motor up or something like that. So I will have to check that and try again before I go any further. That being said It did shif into 4hi yesterday once when I tryed it, the other times it just made a clunk and the light flashed and went back into 2hi. So it is working, just not all the time..

Also, one thing that I keep forgetting to mention in my posts is that when you have driving along with the heat setting on windshield and floor setting, all of a sudden it will start blowing from then dash vents for a few minites and then stop. This leads me to believe it is something in the vacum due to that all being controled by vacum. This was happening before I changed the hose's and it just did it again last night.


I guess if that all doesn't work I will try the vacum switch on the t-case, your right it won't be easy laying on the garage floor but changing those vacum lines was a B#*ch also laying on my back...LOL

What about the switch on the dash, what is your thoughts on that, is it possibly causing the problem.

Thanks for the offer on the part, is that a dealer only item? If not I will check an see what my parts connection guy can get me for a price and if its not reasonable then I may take you up on the offer.

Thanks again.
Scott

 

Your vents are tied into the same vacuum system as your t-case. In fact they both get thier vacuum from the same tee fitting.

 

Ya, I realize that so it makes me think that the vacum switch on the t-case mayin fact be bad because I have change all the vacum lines that come from the t-case and it still doing it.
Wife just got back from work so I will have a go at it again.

Scott