RickyT

My 4WD doesn't work! I put the truck up on jack stands and this is what I found:
In 4 HI the front driveline turns but the front axle doesn't engage.
In 4 LOW you can hear the transfer case engage but the front driveline doesn't turn. I think the 4 HI problem is in the Actuator on the front axle. I think the 4 LOW problem is in the transfer case. Does anyone know of a common componet that breaks in the tranfer case, or has experienced this problem?

hondo68

I reciently had my transfer apart and the only thing I can think of that might make the front engage in hi but not low is - maybe a circlip sliped out of it's grove so the dogs are not engaging. At any rate it's going to have to come apart, so bite the bullit and go for it. The only reason I took mine apart was to replace the seals, and the chain as a precaution. The manual trans juice was leaking into the transfer, so the trans was kinda dry and the transfer overfull.

On problem #2: There is a switch on the transfer that closes in 4wd positions, make sure it's closing. Also there's a spring loaded plunger switch on the front axle (smaller one, on top) that must be working. Try hot wireing the wires going to these switches and see if the front axle engages to the driveshaft. If the front part of the diagram by the transfer lever is not lighting up in 4wd, you have an electrical problem with the front axle.

toklatman

Check the 4WD actuator switch. The OEM was an electrical unit, the replacement is gas filled.

Mine went out at 50K, the repair shop said this was a common problem with the old style switch. We have also replaced several on our fleet of Suburbans.

It's a 50 dollar part