4 Wheel Drive Not Engaging

I have a 1997 Tacoma 2.7 liter with the 5-speed manual transmission with 280k miles. The 4-wheel drive is not engaging (and the 4wd indicator light on the dash is not illuminating). I noticed that the half-shaft between the transfer case and the front differential spins freely when 4wd is not engaged, but when I engage 4-high the shaft locks, so the transfer case seems to be mechanically engaging. (My truck uses a lever to select the various drive modes, not a push button system). I also checked the 4wd fuse and it seems to be good. Should I check the auto-locking hubs next? Please help steer me in the right direction.

 

Yes- or more specifically, the ADD Actuator. You should be able to find some resources here or on the web with instructions on inspecting them...

A '97 J-shift, is likely going to be vacuum actuated, so it might be as simple as a broken vacuum line, or you may have to rebuild or replace the actuator.

 

Most likely the hubs are not locking. This is why it's important to engage 4X4 and use it for a short time on a regular basis. It keeps everything lubricated. I used to own a 1991 Cherokee that my wife drove. It wasn't used in 4X4 regularly and did the same. No new parts were needed. Just take the hubs apart, clean out the hardened grease that was preventing the hubs from engaging, re lubricating then reassemble.

Manual locking hubs will do the same thing if not used regularly too.

 

There are no moving parts to service in the hubs of ADD trucks. The disconnecting happens in the stub shaft:

 

If the indicator on dash does not illuminate you should check the switch underneath if your taco has one. That was found to be the issue on mine a few years ago when the light would not come on and I was stuck in the snow in a valley with 4wd malfunction

Do you hear a click sound underneath when moving the j shifter?

 

time to upgrade to manual hubs

 

@Black97v6MT - where is the switch underneath that you are referring to?

 

Before you go about pulling that actuator out I'd put the truck up on 4 jackstands, fire it up, then select 4wd, and then use a handheld vacuum pump connected to the actuator vacuum port to try and suck the selector fork into 4WD.

I managed to get the 4WD working in a 98 4runner using that technique after I had already gone through the hassle of pulling and reinstalling the actuator.

 

it will be somewhat similar to this except it will be on the passenger of transfer case afaik
the similar looking switch into the transmission is the reverse backup light switch

https://youtu.be/MX2YzfNb6yc?si=oTV0NPu6p2A4V36u