So I got my '06 back in July and I can't remember if it worked then, but I know that my selector doesn't change between 2hi, 4hi, and 4lo.

The light on the dash with the car w/ wheels turned is green, so I assume that means I am in 4hi. Also my mileage is crappy even on highway (16-17 mpg) so I think I'm right.

How do I find out what is wrong without getting raped by a shop? It's not under any kind of warranty.

Any help is much appreciated!

So the switch wont turn? Or you turn the switch and nothing happens?
Yes if the light is on you are in 4hi.
I know some guys have had problems with the system who never use 4x4

The switch moves just fine, but nothing changes either audibly or visibly on the dash.

I don't anticipate needing 4L much, but it certainly would be nice to be able to get 2H and save some gas!

You wont really see any increase in fuel economy once you get it working since those axles are always spinning and causing a slight parasitic drag.

But you should def strive to figure out the problem. I would start simple and look at the switch to see if it's damaged or not, then fuses and also locate the computer that controls the 4wd behind the dash an maybe try unplugging it and pluggin it back in(couldn't hurt right?) then onto more tricky things like the encoder switch on the transfer case that actually tells it to shift in and out of 4wd. Then finally something mechanical.

Driving on dry pavement in 4hi is not good on the driveline. I would check the 4x4 actuator. I think there are some threads around here that will help ya out. But the only ones ive read are about guys who cant shift into 4lo.
Some have fixed it by loosening the actuator and lightly tapping it with a rubber mallet. Hope you don't need a new one, those are about $2500 if you have to have it fixed @ dealer.

He has a 4th gen so the Torsen center differential will not cause drivetrain wind up like traditional part time 4wd. If that were the case then every AWD car would be broke down on the side of the road.

When you go around a corner, the rear of the vehicle takes a shorter path than the front. As a result, the rear driveshaft needs to turn fewer revolutions than the front driveshaft.

In a part time 4WD system, the front and rear driveshafts turn at exactly the same speed. This is not a problem when offroad because the tires simply slip. But on dry pavement this can stress the drivetrain.

But the 4Runner in question is a 4th gen. It is not a part time system. The 4th gen has a Torsen center diff that allows the front and rear driveshafts to turn at different speeds. So you can drive a 4th gen on dry pavement in 4wd without any damage. In fact the 4Th gen V8 is fulltime 4WD -- it is ALWAYS in 4WD.

As long as you do not lock the center diff and turn, you won't hurt a 4th gen by driving on dry pavement in 4WD - it is designed to be able to drive in 4WD on dry pavement.

oops my bad guys! I knew the v8 was full time just thought that the 4x4 system in the v8 was its own beast. Toyota should have made it a selectable system like the v6.

Thanks for clarifying, I was always careful not to keep my truck in 4x4 on dry hard surfaces. after all this time. lol

There is little difference between the 4th Gen V6 and V8 4WD systems. The V6 has a 2WD mode; the V8 doesn't. Both have a hi and lo range. Both have a lockable, limited slip, Torsen center diff. As a result, both can be driven on dry roads in 4WD. Just don't lock the center diff (or if you do, avoid turns).

Time4Hockey,

If you're in 4hi center diff unlocked, that's by far the best place to be stuck. Mileage probably wouldn't change as much as you expect going to 2wd. Most of the mpg difference between your truck and a V6 2wd model is due to the weight of the 4wd hardware. If the mpg hit is definitely in the full digit range, perhaps the center diff is locked. Easiest way to test is simply driving straight down the road (keep the wheels straight).

If the diff button works and you don't care about low range, you might consider doing nothing and enjoy the AWD, especially if the cost to fix will be high.

The differential is fine, and I can engage or disengage that. Hoping it's just a switch issue, so I'm going to try a few of the things rebelbowtie mentioned above.

If it's expensive though, you're absolutely right. I will be enjoying AWD!

I’m looking to buy a 2004 sport edition 4wd. It’s stuck in 4H and has been for some time. It also has the VSC TRAC and VSC OFF dash lights on as well as a Check Engine Light. The CEL is for a bad O2 sensor per the code. Would the VSC system lights that are on have any bearing on the 4H issue? I’ve seen that a simple zero recalibration can fix the 2x VSC lights, but wondering if there is more to it.

Thanks!

CEL triggers those other two automatically, so possibly no relation to being stuck in 4H. Assume you've driven the truck? What happens when you try to switch to 2H?

I'm assuming this a V6. It's often not known or obvious (but is mentioned above in this thread) that the V8 is 4wd only (aka full time 4wd).

Predicated on that assumption, it's probably fair to assume the CEL/christmas tree lights are not related to transfer case issues. I keep an eye on threads about t-case problems and I don't recall seeing many people talk about getting dash rainbow in addition to 4wd problems. Hopefully someone corrects me on that should I be mistaken though.

There's many threads talking about issues with the actuator in the transfer case ceasing up if it's not cycled often... or leaking, or just generally being ornery.

I will admit I'm less familiar with the V6's 4wd setup on the 4th gen, but assuming it does work like the late model 3rd gen setup with a solenoid operated ADD, it is possible that the ADD system is not functioning. This can cause the green 4wd light to flash endlessly. Of course, so can a t-case problem. Normally the problem is being stuck open (in 2wd). I'd imagine it's possible for it to be stuck closed in 4wd if the solenoid crapped the sheets. There is probably a testing method in the TSRM detailing how to diagnose a bad actuator... and if you are so interested I can likely find it.

A friend of mine bought a taco and found out later that the ADD actuator had been smashed by a rock... so, anything is possible.

The 4wd issue turned out to be a broken plastic switch. I reinforced the back of it with hot glue and it switches and latches into 2wd and 4wd! Thanks for the response!