switchback

I did a search on this and found no returns so thought I would start a new thread on the subject.

Just bought a 1999 4Runner SR5 and after reading a few things in the owner's manual I am now wondering if my truck has ADD (automatic disconnecting diffential) or not. Do all 1999's have this and if not, how can I tell if my truck has it or not? Furthermore, what is it and what are the pros and cons of it? Please bear with me as I am new to this whole 4WD thing. I am coming from full-time 4WD and AWD vehicles such as Subaru's and need a little advice on this part-time 4WD thing.

Also, I know that my truck has a locking rear differential but am not sure as to when this is needed. Sounds like, from what I have read on other threads in this forum, that it is used only in 4L and when the truck is off-kilter to where on rear tire is in the air. Am I getting that right?

calrockx

yeah, you've got ADD. or rather, the truck does. i think so anyway.


the rear locker will come in handy in low traction situatins. you've got the right idea on when to use it (when a rear tire is off the ground or spinning). it'll vastly improve traction and may just help you up that hill/unstuck. wheelspin=bad.

mt_goat

I'm not sure on the first question, but on the second you will want to use your locker when ever you have a problem with your wheels spinning too much. Like if you get stuck in a snow bank, or stuck in mud, or climbing a steep trail with loose rock. It will also help when going down a steep trail and using your engine braking, the locker will help keep one wheel from slipping.

When you don't want to use it is when you are driving on icy roads because you will fishtail more with a locked rear diff. I like to say a locker is great for getting you out of the ditch, but it will also put you in the ditch quicker. You also don't want to use it while on high traction surfaces, especially while turning.

I don't know about the e-locker, but my ARB rear locker can be used in 2WD, 4W low or high. I have sometimes used it in 2WD when I got stuck but didn't want to get out and lock the front hubs to use 4WD.

switchback

The only reason I was confused in the first place was because the manual said "With an ADD do this. . . blah, blah, blah" and "Without an ADD do this. . . blah, blah, blah" so I was assuming that not all 3rd gen. 4Runners were equipped with an ADD. I don't even really know what it is. I called Toyota and they ran my VIN and came back saying that I don't have an ADD on my truck. Now I'm really confused!

mt_goat

Do you have to get out and lock your front hubs to use 4WD? Here is some info on how the older ADD system worked, I don't know about the newer trucks. http://www.off-road.com/toyota/tech/add/index.htm

calrockx

i could be wrong. but i sure thought all 3rd gens do. my 2002 does. i'm sure someone will come up here quick and correct me if i'm wrong. :pat:

switchback

Yeah, I don't know. I am going to read that link that Mt_Goat sent and see if that will help me determine if my truck has it or not. Thanks for the replies though.

ChickenLover

I'm pretty sure you have ADD. You can't always trust what the stealer tells you. Half the time you've got some numbskull who doesn't even work on the trucks answering the phones. With an Add front end, your front driveline,diff, and axleshafts are always turning when the truck is moving. When you push your 4wd button the axle shafts extend (via a vaccum actuator) and connect to your cv shafts, putting you in 4x4. This system is pretty cool cause you can shift into 4wd at virtually any speed as long as your front and rear tires are spinning at roughly the same speed. But, on the other hand it takes power to spin your driveline,diff, and axleshafts when you aren't in 4wd.

superjoe83

yes, you 100% do have ADD '95 was the last year of manual hubs on 4runners

Cebby

What he said...