I just tried to test out the 4WD on my 91 4runner and it won't engage. I hear a "click" behind the dash...like a switch engages but no 4WD light and I tried it on a hill and just the back wheels spin. So its not engaging for some reason. Anyone have any suggestions?

 

If it ADD the lines are probably clogged.

In the front passenger side wheel well towards the front bumper you will see a round canister with two lines running too it. (Behind the plastic in the wheel well) Pull the lines off and make sure its not plugged. Thats where mine always gets clogged. I just stick a small nail into the line on the canister and un-lodge the crap.

Also from these line you can check for vacuum pressure and try tracing the problem backwards.

 

First thing to check is all the vacuum lines for the ADD. The click you here is probably the ADD relay, which means the transfer case is engaging. Check the lines at the VSVs on the inner passenger side fender, at the vacuum reservoir under the fender and at the front diff. This is the usual problem.

 

I just checked them vacuum lines coming off my diff to a vsv...good and I checked the vacuum lines coming off the canister....good.

 

Did you check the Nipples (Can't think of word) On the canister itself. Thats where mine ALWAYS get's clogged. I use a small drill bit or nail and try to poke it threw the Nipple's (Where the lines attach) into the canister.

Ie: Pull the line's off the canister, Stick nail or drill bit into the hole's on the canister. Wiggle. Re-attach lines. Test 4x4

 

I have the factory manual in pdf files, send me an email address and I'll forward the ADD section. I tried posting it here but the file's too big.

 

Thanks...its jnsnburg@aol.com

 

'You've got mail'

 

Just checked them with a drill bit...all clear

 

AOL....gotta...love it...i guess! I used to have DSL before my bills ate me alive...now its back to slow dial up! thanks again man..

 

Just wondering.....my brake light was fading in and out and now it stays on. Could this have anything to do with this problem?

 

Hey do you have the vacuum line diagram for the front diff to the vsv's?

 

Nope, sorry don't have that

 

well i just tested it...it feels like it locks into 4wd...even the 4 wheel lo seemed to lock in...but i test it on a hill and back wheel spin and no indicator light. i've had so many problems out of this 4runner...

 

no other suggestions?

 

Start tracing your vacum lines. You have a leak or break somewhere.

Can you feel suction on the lines going to that canister ? One should suck one should blow.

hehehehe

 

Well I just had my g/f go in the truck, engage 4wd and put it in gear and i pulled each vacuum line individually off the canister to check for vacuum or no vacuum and either one isn't doing anything really. almost feels like a slight vacuum but nothing noticeable on one of the lines. heres a post that i looked up earlier...might be my problem but not sure.


first off; thanks to all for the help. Heres what happened.. i brought the runner in to the stealership to do the bushings on my brake pedal as it was floppin side to side. i would have liked to do it,, but time is limited. turns out there is a relay, fuel pump relay, kind of connected onto the brake system bracket,, well it seems that mr.fixit at toyota felt it wasnt neccessary to plug this relay in. im not making assumptions that it was intentional.. but wow! how do you miss that, especially when the connection is a clear yellow color and is dangling! wow! anyways i plugged it in and everything is working including the 4wd light. cant wait till monday when i pick up some touch up paint. fists will be flying.. thanks again to all of you for the help, and now i can hit the trails. this place is great.


I noticed a "click" come from this same box that is supposedly the add relay i guess....i could feel the click when i would engage 4wd. hate to spend the money and this not be it though.

 

Let's start with the easy things first. You don't have manual hubs, do you? How do you know the passenger side tire isn't spinning?

 

no manual hubs....but although i did do a continuity test on the relay and i had continuity on pins 1 and 3 but no continuity on pins 2 and 6. and in the next step it says verify continuity on pins 1 and 4 with voltage to pins 2 and 6. well i figured if voltage was supplied to pins 2 and 6 then that is what actuates pins 1 and 4 to the differential to lock it in. that sound logical?

 

Like Robinhood150 said.. make sure the passenger side tire is spinning if you have an open diff... I thought my 4wd was out, but turned out that it was the other front tire I couldn't see that was spinning.. stoooopid oped diffs!