Hello~~~>>>>PLEASE HELP…!!!
I've got a 1991 4Runner, new rebuilt engine, which is running great.
BUT...now my front axle (4x4) is Not engaging...!!!
The Transfer Case is working but there is NO drive to the front wheels.
I also noticed the 4x4 Dash Light has gone out.

This is a Stock 4Runner / front IRS unit with NO warnings of any issues.

I am selling the rig and a buyer took the rig to a Firestone Shop for a Vehicle Inspection. They told him the 4x4 Not Engaging.
The front wheels are NOT turning when the rig up in the air on the hoist and is put into 4 wheel Low drive mode with engine running. (Lever moved into 4 low/4high)

I did not go the the shop with the buyer so I was not present during the inspection.

Got the rig home and into my workshop, I jacked up the driver’s side front wheel, put the tranny into first gear, with the transfer case selector into 4 Low. The front wheel spins free...???

Can anyone tell me what to look for? Could this be an electrical issue to look for? I just don't understand what the Sam Heck is going on here???
There has never been any drive train issues; NO bad sounds or whines coming from the drive train. When driving the rig in 4 Low it acts like it is all working OK. Low MPH with the RPM spiking fast. I haven’t had time to go out and test it in the dirt doing any hard climbs. NO Plates or insurance.

This blows me away and scared away the Buyer...((
I'll go outside and set the rig on stands so I have all four wheels off the ground, fire up the engine and look to see if the Front Drive Line is turning.
Then come back here to seek advice.

Question...does this type of 4x4 need to be on the ground with traction/pressure being applied to the front wheels for power to be applied to the front wheels and turn the front wheels???

SORRY for being so LAME...I hope I am making sense for you all.
Plus what do I look for concerning the 4x4 Dash Light going out...?
Is there a FUSE that may be causing these issues…?
This truck has mostly been sitting for the last two years.

PLEASE HELP
Many Thanks,
Rex

 

I had a similar problem recently and it was the hoses going to the actuator. Here is the link to the thread I posted https://www.yotatech.com/forums/f116...gaging-196187/

There are many things that could be going wrong, but if you can trace the vacuum lines around the rig you will probably be able to find the problem. My 4wd hose going into the actuator was loose and pretty dirty, but once i cleaned it and reatached it better the 4wd works like a charm. In my link there are also some other suggestions on what the problem could be. Also try checking the components in the diagram in my link. Hope this helps.

 

if its the ADD system during the rebuild you could have got some vaccum lines backwards. 2 be honest the really only thing i can think of could be that why the light is out could be the blub is blown or the solienoid under the dash went out. you just need to check the vaccum lines to make sure they are on correctly

 

oh, and fyi, if you take the acutator off, remove all hoses and place it on the other side it will work just like you didn't have that stupid acutator on it, did that on my t100, haven't done in on the current runner yet but may be doing that because you reminded me of failure when I need it.

 

http://www.off-road.com/trucks4x4/ar....jsp?id=399612

 

My light stopped coming on when my vacuum line got loose so the bulb could be perfectly fine. After I fixed the problem the light started coming back on, thats how I figured out it was working again. My dad was under the car tracing vacuum lines and happened to wiggle the one that was loose while I was shifting it into 4wd and the light flickered so we randomly found the loose line.

 

Howdy Fellow Yoto Head,
THANKS BIG TIME~~~>>>this really makes since and I pray iot is the cure.
It is such a pleasure knowing there are Good Peole out there willing to HELP.
It is getting late so I will follow up in the morning.
Thanks Again
Rex...))

 

Fellow Yoto Heads,
I checked all the vacuum lines valves and everything looked OK. I went down and purchased a Hand Held Vacumm pump to do the A.D.D. direct test and Hot Damn the 4x4 Engaged and the 4x4 Dash Light Came On...))
Now I knok the Front Axel assy is OK so I have to trace down why the Vacuum is NOT getting down to the ADD unit.
OR...I am seriously thinking of installing Lock Hubs and running a direct vacuum line to the 4 wheel drive side of the ADD unit which will keep the ADD unit in 4wheel drive mode all the time and I use the Locking Hubs to Free Wheel on the road. This will allow me to remove a ton of crap whaich HAS Gone Bad and stuff that can go Bad in the Future.
What are you thoughts of going this way...???
Many Thanks,
Rex M.
PS: I had three 4Runner a few months ago. I sold my 1995 for $5,250...))
I paid $5,250 for the Runner four years ago...SWEET...))
I still have a buyer interested for the 91 4Runner willing to pay $4,000.
I plan on keeping my 98 4Runner. I bought the 98 with a bad engine. I bought a used 3.4 for $900 did the swap...the 98 runs GREAT. This left me with a tired 3.4 engine sitting around so I went ahead and did a complete Rebuild on thast engine so Now I have a NEW 3.4 ready to go into another rig. If anyone knows of a Truck or 4Runner 96 to 2002 with a tired or dead engine and wants to sell it PLEASE let me know
Thank Again...!!!

 

instead of running one line to the front diff you could take the aucator off and lock it in the 4wd postion and install it back and block off the vaccum lines and get asin hubs and go muddin!!

 

Yeah FireMan,
That is what I am thinking of doing. I located a set of locking front hubs @ $70 for both hubs.
What is the best way to lock it in the 4wd postion once I remove the aucator?

I am thinking it would be wise to bypass all the vacuum crap which will go bad again down the road.
Thanks,
Rex M.

 

I highly recommend the manual hub swap + bypassing the ADD. The 4wd was not engaging on my 4runner when I first bought it, so I swapped. Much betttttter. works flawlessly now

 

when you take off the front aucator you will see a fork the 2wd postion is where you can see it 4wd is when it is closer to the tire i have heard of ppl using a hose clamp and locking it in the 4wd postion if you need help with it let me know through pm and i can help you get it working