Well guys, you know what I say, another day another problem. So for the past 2 weeks or so the roads around here have been straight ice pretty much and I noticed even in 4x4 I was sliding around a lot and sometimes would not move at all and just have my tires spinning out! Today I was coming into my driveway to park it, I put it in reverse and tried to back up in 4x4 and I wasn't going anywhere! So having enough I told the person with me to get out and see what tires are spinning, turns out only both rear wheels were spinning and nothing from either front wheel! So now I am trying to figure out what is going wrong here, when I shift from 2wd to 4wd I can hear the clicking in the tcase and the light indicates it successfully shifted into 4x4, but indeed no power is being delivered to the front wheels! Any ideas on what I should check out would be greatly appreciated. I think I want to start by checking the plunger to see if it pulls the cable when I shift into 4x4, it's just so tight in there with the battery in to see what it's doing.

 

Just jack up the right front wheel, leaving the left front on the ground. If the front axle is locking in, you won't be able to turn the wheel by hand. This is of course with the engine running.

Do you have 3-button or 4-button auto?

 

You might be able to get a hand on the front axle vacuum actuator to feel if it moves when another person selects 4HI. Of course the engine needs to be running, trans in PARK. Do not want you to get run-over.
Better way is to just remove the battery and battery tray to access the vacuum actuator. This way you can see if the actuator is torn or the cable is rusted and not able to move.

 

An easy check is the underhood vacuum lines that could be leaking.

See the link in my signature for more information.

 

Thanks guys!! Sorry Les, to clarify I have the 3-button switch. I did a diagnosis today with some tips from you guys and think I have found the problem. I started by jacking up the passenger side front tire and trying to move it with the engine running in 4x4, I indeed could move the tire. I then tried to manually pull the cable and lock the axle in, when I pulled the cable and I could not move the tire anymore. Following this I hooked up my air compressor to the vac line going to the actuator, right away it was clear there was a huge leak and sure enough I found my vac line was in 2 pieces, melted by the exhaust manifold. Now, Christine I have seen the vac hose diagram you posted many times and it has helped me a lot before, but I think the diagram is for a 4-button switch and the routing on mine is a bit different for the 4wd. I have the 3 lines coming out of the transfer case and one of them is this line that goes to the actuator. Does anybody know what the size of this vac line is?

 

Glad that you found the problem!! With mine I melted the wiring to the fuel injectors after engine R&R.

 

Thanks Les! Right when I saw the melted hose I had a flashback to dropping the engine in and that hose was pretty tight to fit around the engine, I don't think it ever got moved into a better position after wrapping it around the side of the engine either LOL. Anyway, I got some new vac line today with some new corrugated heat shield and got to work on replacing the lines, I decided to replace the melted line along with the engine manifold vacuum line to the transfer case. When I took the 3-way plug off the transfer case switch there was a small amount of fluid I noticed coming out, I came to find out it was mostly all in the manifold vacuum line, I'm going to get a new switch next time I'm at the parts store and replace that also! I got it all back together with the 2 new vac lines and jacked up the passenger front tire to see if I fixed the problem, and now with the engine running in 4x4, I am happy to say I can't move the wheel anymore! Thanks for the help here, everyone!

 

You're welcome! Good work!! Happy motoring!!

 

I'm wondering if the 4wd wasnt working when you had the accident on the trail, causing you to lose control and bang up the front?

 

Do not use the Dorman transfer case vacuum switch. The one I installed lasted less than two years. I replaced it with the AC Delco D1754C. So far so good.