Currently undiagnosed 4WD issue...help.

So I'm going to start out by saying I have zero mechanical skills and I have no one to work on my truck outside of paying a mechanic.
So if you can explain ideas in ways that my mechanically simple mind can understand and express to a mechanic (assuming I can find one that will listen but that's another story) that would be awesome.

The truck;
2000 Tacoma, v6, TRD, 4" lift, auto hubs, vacuum system run, transfer case shift on floor, closing in on 300,000 miles.
150,000 of those have been almost entirely dirt road miles, all this truck is mainly for is hunting.
During the winter I will often do hundreds of miles in 4WD both low and high in one day.

What it is doing - or should I say not doing;

It randomly throws itself out of 4WD.

I first noticed the light was going off and I thought well maybe the light is just going off, then I started feeling like I was spinning on occasion when I shouldn't be.
Then I realized when the light goes off it has actually taken itself out of 4wd, it will do that in both 4 high and 4 low but less frequently in 4 low.

On occasion I can hear it coming out and going in without my touching it but the shift never moves out of gear by feel or sound, I just hear it 'click'.

When it has taken itself out the driveshaft spins but the wheels do not.

I took it to the mechanic, they of course could not get it to do that while they had it or on the hoist, they suggested it was the actuator so $400 later I had a new actuator, took it out hunting, still doing the same damn thing.

Took it out with my neighbor to watch and we got it to throw itself out pretty easy which was when we finally saw that the driveshaft moves when the tires are not. So during that time in order to try and get out of the mud pit I got it wiggling along in 2wd I was horsing it, then it caught 4wd and when it did it sounded like a gunshot, it wasn't your typical complaintive thunk like when you go into 4 low too fast, this was loud and I felt it in the truck.
It was associated somewhere with the front end.
Then I realized it had done that to me one day in the snow, I had stopped and when I went to move forward again it lurched and made that sound, I thought I had hung a rock up and spun it out but in retrospect it was whatever that was.

I took it back to the mechanic they cannot find the issue, they told me to take it to the dealership, I can't afford the dealership, I also can't afford to keep throwing money I don't have at 'maybe'.

In the last year and a half I have broke the lower drivers side ball joint out twice.
the latest also bent the axle and that was replaced. But the last time was in September and the 4WD has functioned fine up until just when it started this like almost a month ago now.
I don't know if that is even related.

I need my truck back.

Thanks for input.

 

The load clunk/gunshot sound was something major breaking. The front driveshaft still turns but no 4x4 lends me to believe there's something broke in the front differential. As far as your original problem of the 4x4 going in and out. That sounds like a vacuum issue to the actuator.

 

Oh and lower ballpoints OEM Toyota or nothing. In your situation of off-road use. Your just asking for another failure with aftermarket ball joints.

 

But it appears to still be doing the working off and on after both occasions of the 'explosion' sound, so kind of carrying on the same, wouldn't it have gotten worse if it was something mechanical inside the differential?
If you had a guess at what had broke what would you say?

 

This kind of stuff is difficult to diagnose not in-person.

If the front driveshaft is actually being spun under power from the transfer case (and not backwards from the wheels spinning), then the problem should be "downhill" from that. Otherwise, you could have an issue with the transfer case sending power to the front driveshaft.

I first thought it was the actuator, but that's new. I would still check and see if it is installed correctly and getting vacuum.

If that is working properly, but the front is still not getting power consistently, I'd say there has to be some kind of issue with the front axle and/or differential. Perhaps rsome stripped off teeth from the pinion and ring gear? Roughed up carrier and spiders? That would be where I look next.

Try spinning each and both tires and see if they will spin each other and spin the pinion and driveshaft. Have somebody hold the driveshaft still, and a person at each tire. With the actuator working, spinning one tire will cause the opposite tire to spin the other direction, and visa-versa, with some resistance felt at the driveshaft. Holding one tire still while the other is spinning should make the driveshaft turn. If this does not happen, or there is not regular, consistent feedback to the driveshaft, I would guess the problem lies within the differential.

Best of luck troubleshooting and keep us posted.

 

I wonder if the loud banging is the sound of the axles disengaging under stress, might be the issue and not the front diff. If something in the diff was busted I'd assume it wouldnt work in 4wd at all.

 

Well supposedly the spider gears etc. were all good.
I did take it to a new mechanic and they say they found the problem and guarantee it to be fixed (we shall see my trust level is low) they said it was a broken wire inside a harness that runs the 4wd...so they are also working on a part of my steering that my stupid lift has worn out.
Once that is done I guess I'll find out if it's really fixed.
I guess the best explanation for working and not working was occasionally it got enough contact to work (or not) while bouncing around.

 

Sure hope you've figured it out! Wiring problems are never fun hunting for. Finger's crossed that does the trick.

 

Makes sense, a bad wire or partially compromised one would cause those symptoms I imagine.

I had a bad wire running to my Hella lights, caused them to sometimes work and sometimes not.

 

I hope so, hopefully I won't be back with more questions anytime soon...

 

Did you get it fixed? Guess I should say is it fixed?