Four wheel drive not working?

Jack up the front of the vehicle, be careful if you have air suspension system as it could inflate. To turn off, the switch is located in the area of the right kick panel. After the vehicle is jacked up manually turn each wheel, make sure the vehicle is put in the 2 wheel drive mode and in park. Check the cvs joints one could be going bad. If the wheels are hard to turn as if there is a noise on the left then check the one on the right. Sometimes with bearings the opposite is the one that is bad. Check for any other noises to make sure the 4 wheel drive is off. If you hear the clicking when both wheels are turned or they hang up the vacuum shift motor could be hanging up, keeping it from disconnecting all the way. Then check the wires and vacuum lines going to the shift motor

If you are sure the 4wd actuator on the transfer case is working, then either the hubs are bad or there is a vacuum problem to the front differential / axle. If the hubs are bad, they will usually make a grinding sound when they slip. If you hear nothing, then check to make sure there is vacuum to the front axle. If the axle doesn't engage, it doesn't matter what the transfer case does. It won't work.

Manual or auto locking hubs?

Does it work in 4 low? Or just 2x2?

Put vehicle in 2x2 and verify front drive shaft turns freely leaving transfer case to front diff. Then lock vehicle into 4x4 and see if the transfer case engages and the drive shaft will not turn anymore. Does this happen or no matter what happens to push button it stays in 2x2

I think somebody replace the front end and could not find the right gear ratio, take the cover off and check the gear ratio make sure it matches the rear before you destroy the transfer case

Before replacing the switch, have you checked to see if there is power to the actuator on the transfer case when you shift to 4lo? The actuator may be bad. As far as a differnt switch, I would recommend trying to find a good one from a salvage yard.

Let me know.

Joe

On these old systems, there is a motor that runs a sun gear in the case. As it moves in and out it will trip a switch that illuminates the lights.
Check the motor for operation. If you dont know how, let a shop check it for you to verify and give you a bid.

Roy

With the selector in 2 wheel shift to 4 wheel, do you hear any noise or feel anything? If not raise the front of vehicle where it is stable on jackes and check the wiring and vacuum line if equiped, going to the front carrier shift control, some are done by vacuum and some electricallly controlled. With someone in the vehicle have them change the selector to see if the shift control is working.