Godzilla

My 4WD light is not turning on at all when I shift into 4wd hi or low. My transfer case is engaging and it looks like all the tires are spinning. The only thing that is off is that the driver side cv is a little shaky. Is this the cause of the cv or could it be just that a wire somewhere is not connected? I had it in 4wd on sunday and the light was on during "light off roading" and was working after. Any ideas? All help is appreciated.. Thanks
(92 4runner 5spd 3.0)

keisur

bulb is probably burnt out. sometimes the tungsten filament, after burning out, will hit the other post just right and stick for a while causing the light to work, then a sudden jolt lets it loose and it's off again. I'd say pull the guages and check it.

NorCalVP

Do you have ADD? if so, make sure your front axle is engaging. I had a similar problem when i installed my supercharger on my Taco (a long long time ago when i was IFS) and i forgot to hook up the ADD vacuum line. i didn't realize it until i actually went 4 wheeling a month later.

I'd check that before you tear your dash apart.

Steve

Godzilla

yeah the last thing i want to do is tear open the dash, for some reason it causes stress! where is the vacumn line located, where should I look for a loose line? and yes i have ADD.

keisur

the guage isn't really "tearing into the dash," it's alot easier than getting to the stereo. on my vehicle it's 4 bolts, 4 screws and about 2.5 minutes.

Godzilla

i was reading some previous threads which took a bit to find about the 4wd sensor. Is this located on the front differential?

NorCalVP

On my Taco and 4Runner the solenoid's were on the drivers side inner fender, they were brown and blue pieces, with two vacuum lines comming out of eacy one, and an electrical plug. I think yours should be on the passenger side inner fender.

I'd find out if they were working by jacking up the front end engaging the 4WD and trying to turn the wheels.

4Hummer

91 4Runner with ADD.
There is a Round Canister in the Passenger Side Front Wheel Well, By the front bumper. It has two Vacum Lines going to it. Check to make sure they are not Plugged. Mine gets plugged up with crap every once in awhile and than 4x4 no Workie.

I just pull off the two hoses, run a small drill bit threw the canister openings and problem solved.

Hope this helps. If you need picks let me know.

Godzilla

if you could post pics of that it would be great, i have an idea of what you are talking about. do you have any pics of where the 4wd sensor is on the diff? thanks

4Hummer

Ill take some pics when I get home today.

kyle_22r

there's a 4wd indicator switch on the transfer case

Flamedx4

This help?

eric-the-red

The switch on the transfer case controls the ADD relay which in turn sends power to either the engage or disengage vacum solenoid, the ones inside the front fender. The vacuum then activates the ADD system. There is another switch on the front diff that senses when 4wd is enagaged and turns on the light. If you look on the front side of the diff you'll find the electrical connection for this.
If 4wd is working and the ADD is engaging then the problem must be the switch on the diff, or the bulb. Try removing the electrical connector from the diff and jumping it with a wire, (on the connector side) , then put it into 4wd and check the light. If the bulb works it should light, if not it's probably the switch.
This is assuming the 4wd is actually engaging, also check the vacuum lines like someone suggested.

Godzilla

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.

ken.vs.ryu

do you have pics of this relay? my 4wd light is out. what is add?

Godzilla

ADD is the system for 4WD on toyotas. Im not sure on models and years. If you dont have locking hubs then you probably have add. I dont have any pics of the relay, but it is easy to see if you contort your body so you can look up above the brake pedal. there is a small bracket and a black relay attached to it with a wire and plug going into it. this was my problem, however i hear there can be many causes for this light to go out as mentioned in this thread and if you search some others. If you cant find the relay let me know and ill take some pics tonight/tomorrow.