1996 4x4 front wheels not locking in??

I can shift it into 4hi and 4 low and the switch is lighting up right. Plus when I shift into 4low it does gear down, But the front tires still dont turn. So to me it seems like the transfer case is doing its job. I checked the vacuum and it has plenty, but I dont know what to look for now? Maybe some kind of actuator?

Depends if your's is electronically controlled or just vacuum controlled like my 91. First thing to do is look for vacuum leaks on all the hoses. Not sure about your's, but my 1991 has a vacuum actuator located under the battery (must remove) attached to the right front fender well. Check the hoses. The actuator itself could also be the culprit. Leaks are more obvious and easier to detect before buying unneeded parts.

There is a vacuum swith located on top of the transfer case (not front differential as some confuse) it is right at the tail of the transmission. Look on top and you'll see a vacuum harness with 3 hoses going into one connection into a steel plug. This plug is the switch. Disconnect the hoses carefully and unscrew the switch. A new one most likely will have to be purchased from a dealership. Mine was $33.00.

Now, mine is an older one with no electronic 4x4 controls, so do not hold me to my next possible solution. I have heard that the push button types have a solenoid that switches the transfer case into 4x4?? Not certain, but check into that as well.

Good luck!

Dude crawl under your truck,on the transfercase, drivers side on top, there is a vacuum switch make sure the hose connection is on the switch!!!!!!! That is what was wrong with mine!!!!!

I can shift it into 4hi and 4 low and the switch is lighting up right. Plus when I shift into 4low it does gear down, But the front tires still dont turn. So to me it seems like the transfer case is doing its job. I checked the vacuum and it has plenty, but I dont know what to look for now? Maybe some kind of actuator?I just had the same problem...my mechanic manuallly got it to engage and said that there most likely was a burr on the syncro and that was preventing it from engaging...after driving it for a day or so in 4 wheel, the problem was fixed...now I have no problem....he said the cause was most likely from not using 4 wheel drive.

my 94 is push button and its sounds pretty much the same as his 91, there is a actuator under the battery, and a vaccum harness that runs from the actuator down to the transfer case. My truck wouldn't go into 4x4 there last week, I was looking on this forum and someone suggest that I unhook the battery for 5 minutes. It worked, and so far is still working, I guess theres a 4x4 controller under the dash that screws up sometimes, just like every other computer on earth, requires a reset now and then.