OK another question for you guys here on YotaTech. my 92' 4Runner had an unusual problem in how it went out. A couple of weeks ago i would go to put my 4Runner in four wheel drive and it would take a long time to get the 4WD light to come on and the front diff to engage (like 15-20 min, or about 10 miles) but it would go in eventually. Now it wont go it to four wheel drive at all, my book dont tell me nothing on the the operation of the front diff engagement. It now WILL NOT let me move the t-case selector while moving at all (unless i pull hard on it and grind gears), i have to be at a 5 mph or less to move the stick but still wont engage. Anyone have any ideas as to what could be the problem? Thanks

 

Click the link in my sig, and read about the ADD system.

 

Well Mike it sounds to me as if your flux capacitor might need to be recalibrated. It might not be sending the signal to your front diff hence why your light isnt coming on!
Just kidding buddy!

 

look for a thread for 91 4wd flashing, by kdi customs in there is a manual for the add system in there, i think u need to pull the vacuum actuator from the front and clean that out, and go from there, wish u luck and if u need more info let us know..

 

thanks a lot. i checked the link provided by 2DoorRunner and printed it out also saved that link. MUCH valued information on there for this goofy setup. i had a general idea on the design as i had been driving a 93 blazer for many years with the same setup (vacuum actuated front diff) and had several issues related to that one. needless to say the whole system was replaced piece by piece.

 

i ended up just pulling the actuator apart and cleaned it up and put it all back together, worked really good after that. just ideas.

 

this is easy to do? i have yet to look at the system on this truck. i was thinking the actuator would be the cause of my problem, but would there be anything on the t-case that could fail? or is it just a electric switch that controls the valving system? trying to get a mental visual of what im getting into. thinking the system isnt as camplex as people make it seem to be, ive worked with some pretty idiotic vehicle design problems in the past so this wouldnt be to surprising.

 

its not too bad, if u have an auto i think there is one extra sensor on the tranny, other wise easy... when u first put it in 4wd do u hear a click under the dash? it so then make sure u have vacuum at the firewall on passenger side two sliinoids then if u do there then look down at the actuator and see if u have vacuum there. there is a switch two wires going down to it if u pull that sensor u can see the shaft in side the actuator move, if moving slow or not at all then its gummed up if it moves easy then i would think that sensor is bad.

 

Yes the relay under the dash clicks. I think, from what you explain it sure sounds like the actuator. Because it did work fine then about a month ago it started taking way to long to engage but would engage after a looonnnng time. I have the 5-speed manual in my 4Runner thank God. You give some great insight on this four wheel drive problem, hopefully i can take a look at it this weekend and see what i can find out.

 

oh yeah, when u look at the actuator if it doesn't want to more to easy u can take the side plate off bend the black pieces out of way to remove the side cover, to get into where the diaphragm is and pull it out after u remove the pin that holds the fork in place. this will let u take it apart and then clean out the inside and put a little silicone to let it slide. good luck.... any problems ask...

 

Why don't you just switch to manual locking hubs and never worrying about the complicated ADD system again. Also if you convert to manual hubs it puts alot less strain on your front end and is just a lot more reliable.

http://www.4x4wire.com/toyota/tech/add/

https://www.yotatech.com/forums/f128...4runner-76353/

 

Because at the moment the front diff is unlocked. A manual lockout wont help me there, also i like the ease of pulling the stick and magically its in four wheel drive. however i would put the lockouts in for the better gas mileage and the less strain it would save on the moving parts like the CV's but thats another thing to do later on in the project i got into here.

 

you can just lock the front diff in place with a clamp http://www.4x4wire.com/toyota/tech/add/ and then your good to go!

 

manual hubs would be nice, but not easy to find around here.