4WD Problem?

[tannershayde]

I have a 1995 4runner V6 Automatic with 4wd and ever since I purchased the 4runner a couple of years ago the 4wd has never worked. When I first got it I looked at the front differential and saw the wire harness that plugs into the front differential solenoid was missing so I went to the dealer and purchased a new harness and plugged it all in and still nothing. So I looked at the vacuum canister in the passenger side wheel well and all the vacuum lines look like their hooked up. So when I shift the 4WD lever into 4HI it doesn't engage and the 4WD light on the instrument cluster doesn't light up, but when I shift into 4LO it drives like its in LO but still no 4WD light on the instrument cluster. So I don't know what can be the problem the solenoid or something else, so any info is greatly appreciated.

 

[fourwd1]

Maybe the dash light is burned out.
Have you put all 4 wheels in the air to see if maybe it's really in 4wd?
Have you pulled the vac line from each VSV to see if there's a vacuum?

 

[tannershayde]

The dash light could very well be burned out and i have not checked the vacuum or put the truck in the air to see if its really in 4WD but when the 4WD lever is in 4HI and I make a u-turn with the wheel turned all the way to lock I don't feel the resistance like you do when the truck would be in 4WD.

 

[KidVermicious]

The dash light could very well be burned out and i have not checked the vacuum or put the truck in the air to see if its really in 4WD but when the 4WD lever is in 4HI and I make a u-turn with the wheel turned all the way to lock I don't feel the resistance like you do when the truck would be in 4WD.

Ok, so you feel like you've got low range but no power to the fronts, right? I've never had ADD so apologies if I miss something, but I think you've got a switch on the 4wd selector that toggles your vacuum switch, the vacuum switch gives vacuum on one side or the other into the actuator on the diff, and the actuator itself that engages the long-side axle shaft. Run down that line and make sure everything is kosher at each step.

Or just swap to manual hubs already and forget about ever having ADD troubles again.

 

[Pyroboy]

We had the same problem a few months ago with a pickup on a trail run. It had manual hubs swapped in but retained the ADD actuator and there was an electrical fault, causing no 4WD. I think we bypassed the vacuum solenoid to provide vacuum to the ADD actuator. You could also have a vacuum line problem or an actuator problem.

 

[mistersnowman97]

I was literally just about to start a thread about this. Literally everything you stated is is situation with my 94'. The only difference I see is that my 4WD light flickers a few times when I shift it. I definitly feel the Lo-Range thats for sure!! But when i was in some wet thick mud-my buddy said he saw literally no spin from the front. Only the rear. I NEED this fixed!!!! :help:

 

[fourwd1]

I was literally just about to start a thread about this. Literally everything you stated is is situation with my 94'. The only difference I see is that my 4WD light flickers a few times when I shift it. I definitly feel the Lo-Range thats for sure!! But when i was in some wet thick mud-my buddy said he saw literally no spin from the front. Only the rear. I NEED this fixed!!!! :help:

Start checking the vacuum lines and wiring on the ADD unit on the front axle.
The fact that the dash light flickers indicates the ADD actuator is trying to lock the axle. You could have a problem with a VSV or vac line.

 

[Clone of the Mean]

When you put the T case into lo it will feel like your in 4wd because you're engaging a planetary gear that reduces the gearing.

That other stuff I don't know anything about. Dumb question, tho. Does your Runner have locking hubs that are covers by shiny dust caps? I've seen that happen on a few chevy blazers that had "automatic" locking hubs.......

Good luck

 

[Footofgod]

Toyota Tech: Defeating the ADD System - ORN

Here's another option, get rid of the ADD altogether. This especially helpful if doing a manual hub swap, but it still is helpful if you keep the automatic hubs. It eliminates several points of failure in your vacuum actuated 4x4 system. My son and I did this in less than an hour. Only thing you might need to buy is some vacuum plugs and a hose clamp. Do this and you will be able to narrow your issue down if not solve the problem.

 

[fourwd1]

When you put the T case into lo it will feel like your in 4wd because you're engaging a planetary gear that reduces the gearing.

That other stuff I don't know anything about. Dumb question, tho. Does your Runner have locking hubs that are covers by shiny dust caps? I've seen that happen on a few chevy blazers that had "automatic" locking hubs.......

Good luck

The ADD system doesn't use locking hubs, auto or manual, it has drive flanges.