I've read some posts on here that have made me wonder if the vacuum supply on my firewall mounted selector switch is installed wrong. As exhausted as I am, I really can't find the routing diagram in AllData for the vacuum lines leading to that solenoid.

All I know is that my Service 4WD light is on and next week is calling for the snowfall. So, I guess I'm off to isolate as much wrong as I can before I throw money at it

 

I created a vacuum diagram for the NV236 transfer case & placed it in one of the 4wd related threads in the Tech Article section. I think it is in the '4wd front axle clicking' thread. The diagram I created should have the proper routing information for the NV236. I too found any other sources completely lacking in useful information so I took it upon myself to create a single source diagram that got the point across as simply as possible.

This should be the right one, but I am typing out the links from my phone & since I cannot view the pictures on my work computer I will not be sure if it all worked correctly:

 

Yeah, the picture came up fine. So, while I'm not 100% sure why a reversal of the vacuum supply/output on what is essentially a valve would cause issues, I've seen stranger things cause problems.

As soon as I read about it though, I was somewhat interested in diagnosing that part, because it is super easy to get to and takes no time at all to check.

 

B2725 came up. Probably explains why the dash buttons almost have to be mashed. So in that new selector switch goes and that should fix that.

Well the vacuum system was pulling 17" at idle but wouldn't hold it on shutoff. So at least the solenoid was getting something. The hose going to the front axle actuator was way too big to fit on the solenoid, and still too small to fit on the actuator. Leaked like a sieve. Then the tee fitting to the HVAC lines/vacuum reservoir/check valve are junk; it leaks when you wiggle it.

Actuator pulls down good with no leaks to 1/2" with vacuum and hand pressure. The cable is good. No sticking or binding.

The person who conjured up this simple vacuum system must have been getting their pockets lined by suppliers of vacuum line adapters and tees because I personally see no reason why there needed to be this many different sized nipples; other than to use more parts.

It was probably the same people who decided to make the distributor base plastic that was left in charge of a simple system.

 

swartlkk, thanks a million for the vacuum diagram, what a blessing,
im assuming the vacuum reservoir is some place in the driver fender?
at least that is where the lines run to.... thanks again

 

... Lucas electrical products. That's what the back of the 4x4 switch had molded on it.

Changed the switch out and fixed the vacuum leaks. Everything is working as it should and the light has not come back on, yet.

Now the A/C clutch is doing stupid things.
If it isn't one thing, it's another.

 

Lol, I was about to post up check your 4x4 switch. My service 4wd light came on when I had the dash tore apart to swap instrument clusters.

 

Put about 110 miles on it today, with the winter storm and whatnot. Had plenty of opprotunity to change the 4x4 settings and play with the truck

Kinda surpised how well Auto 4x4 worked, but there were a few spots I just engaged 4HI because of the amount of snow piling up. Even 2HI gets around pretty well with the G80.... except climbing hills on ice.

But it all works like it should now, for now. No dash button mashing and instantaneous shifts on the fly. It really moves around good in this muck.

 

I have a missing vacuum line and I think it goes into this solenoid, in the diagram I am missing the red line. I can seem to find the solenoid.