4x4 not engaging

I'm new at this so please give a little grace if I'm the wrong place. I'm not sure that the 4x4 is actually engaging even though the 4x4 light is on. The reason I say this is that I am still slipping around a bunch and it seems like only the back right tire is turning when I start out. I have a 1995 Tacoma. How can I know for sure if the 4x4 is actually fully engaged? The truck has auto locking hubs. If it's not where do I go from here? Thanks for the help.

 

Other than putting your truck on a lift or jack stands and put your truck in 4WD and D, and see the front and rear tire spin (just one front and one rear, because of open differentials)... the only other way is to get into some low traction or steep hill, and see if you have traction in the front.

Oh, you could just jack up the rear tires and see if you can drive forward using the front (4WD).

 

Alternately, you could punch it on soft ground in 4WD to see if you kick up dirt from one tire in the front and one in the rear. This assumes you don't have a locker engaged either axle.

 

Yah, just try and get it stuck! That's how I four wheel a Tacoma... I keep trying, but the darn thing keeps moving... oh, what a feeling!

 

my 1996 did this last winter and it was the vacuum switching valve that sends vac to front diff actuating a sleeve that slides over and essentially engages the front cv axles. instead of fixing or replacing the switch (engine bay drivers side iirc) I just started pulling vac lines to find what supplies constant vac and ran it to the diff. this is essentially the same as driving a manual hub truck with the hubs locked. so then when transfer case shifter engaged = 4x4. mine is no longer a daily driver now, just a firewood wagon.

 

Another way... Find James (2WD) trying to four wheel... and pull him out of a sand dune and up the Diablo Drop Off... You can see my all truck's tires working (4WD Low, A-TRAC and rear locker on) and just James' rear tire spinning:

http://www.youtube.com/watch?v=9m1u1pba4Ps&feature=player_embedded

 

Thanks for the quick replies and the input. I read the A-TRAC/TRAC/AUTO LSD explained article and it was helpful; however, my truck doesn't have any buttons to push, only gear shift knobs. Does that mean that it is always an open differential or is there a way to manually lock the rear differential?

 

RTFM

 

unless your truck came with a locker, you cant lock it.

 

if ya got a TRD Off road package and have that there button next to your steering column you have a locking rear diff. You can only use it in 4low unless you have the grey wire mod or are a TRD OffRoad prerunner.

And yes your diff is always open unless you push that RR DIFF LOCK button or have a mechanical locker which locks when under power.

 

Thanks again guys. I appreciate the help.

 

Perfect answer!!!

 

maby I'm missing something here. my "95" had locking hubs, and a manual 4-wd lever. when I engaged the transfer case, the front axles were engaged. lock the hubs in and 4-wd was functional. thought auto hubs just made it that you didn't have to manually engage and disengage the hubs. could it be that the auto hubs no longer engage ??????? maby i"m off base on this !

 

correct, from what I understand

 

Not sure when Toyota changed from 'manual hubs' to 'auto-locking hubs'.. or if they went straight to the ADD (Automatic disconnecting differential) system, in the 90's.

The difference between 'Auto Locking Front Hubs' and the ADD (all Toyota 4WDs have had for at least a dozen years) is that Auto-locking Hubs require that you drive in reverse a bit to actually un-lock the hubs. The ADD allows shift-on-the-fly into and out of 4WD-High... no backing up.

My dad had Warn Auto. Hubs on his Jeep Wagoneer in the '60's... and it still had the selectable manual hubs in front, but you left them in the 'lock' position... (they would disengage internally, and he even said that he had to drive in reverse for them to unlock).

 

not too familiar with the auto hubs. had them on an "87" 4-rnr. and replaced them with manual lockouts. I believe you'r right about having to back up to disengage the auto. hubs, but still had the lever to disengage the transfer case. W/ the front hubs locked in, I went from 2-4 wd. and back, many times, while driving. the difference is that the front axles and front driveshaft are still turning when the hubs are locked. by unlocking they stay stationary. did this with my "85" & "87" 4-rnrs., and a "95" taco. also with a "78" ford F-150.
a buddy of mine left his girlfriend use his 4-wd to go to work because of bad weather. she said it didn't go for crap and that her car was better. she put it into 4-wd, and never locked the hubs in. only had 2 wd. wonder why they did away with lockouts?

 

put it in 4lo. that way you can see if the t case is at least working right

my bet is front actuator if only the rear wheels are spinning