I just sold my Durango and bought a 98 half ton with the 318 5 speed. Everything works fine, nothing when I bought it, but tonight I was going up a mountain, needed 4 wheel for the snow. It's got air lockers front and rear so it did really well, but when I got back down I shifted out of 4 wheel then while I was driving the light starts to flicker at 30mph then goes solid at 40. 4wd is disengaged. I stopped and turned hard and it didn't hop, also spun the back tires on some ice. 4wd works fine too it's just the light. I'm new to these trucks and I'm nit sure what to look for. Thanks!

 

There's no vacuum leak, I found the 4 vacuum hoses and I can't get that thing out, and I'm not sure where the shift sensor is, I'm guessing it's one of these two

 

The switch for the 4x4 light is on the inboard side of the cad, on the front axle. (central axle disconnect) Probably what is happening is, the t-case is disengaging, but, the cad is having some trouble. Make sure you are getting good vacuum to BOTH sides at the cad. Outboard port in 2wd, inboard port in 4wd.

 

What HeyYou said. The CAD isnt disengaging all the way. I had the same issue a few months ago. Turned out to be a bad vacuum line. I also found out that theres a connector that you can pull off of the CAD and it could be dirty.

 

How can I check for good vacuum? I read that at full throttle if there's a leak the air in the cab will switch to defrost but mine doesn't

 

That's a separate problem.

Pull the connector off the cad.

Start the engine. T-case in 2wd.

Check and see that you have vacuum on the outboard port. (just stick your finger on it.)

Shift T-case to 4wd.

Check and see that you have vacuum at the inboard port.

Vacuum should be equal on both ports. (but, not at the same time.) If not, you have a blockage somewhere, or a leak.

 

If there is adequate vacuum should I just go and replace the actuator and all the switches? I'll go out and try that right now

 

Also are you talking about the electrical connector on the left side of the CAD?

 

The guy I bought it from said he had to a dealer and they said the problem was a switch where the shifter comes through the floor, but I'm pretty sure that it's non-existent

 

No vacuum on an electrical switch. You want to play with the vacuum lines at the cad.