Broken 4WD engagement - what's likely broken?

2003 4x4 V6 AT
I evidently did a bad thing engaging 4wd while my tires were spinning. I heard a very load clunk and bad metal noise. Now the 4wd light is stuck on no matter how many times I toggle the switch. I am not sure whether it's in 2wd or 4wd, but I think it's stuck in 4wd. What is most likely broken and what is the best way to diagnose the problem?

 

You can engage 4WD while tires are spinning as long as you’re under 50MPH and off pavement or the roads are slippery.

The loud noise and clunk could be a lot of things, but my guess is snapped axles. Shouldn’t be hard to check, just get under the truck and wiggle them. If they have a lot of play or you can see that they’re broken, they need to be replaced.

That wouldn’t explain why it’s still “stuck in 4WD” though. Put everything in neutral and then try to push the button back to 2WD. If that doesn’t work, it could be a bad actuator?

 

I was rolling out of a parking lot at 5mph, but tires were spinning a bit. I will check the axles. If that's it, I hope they are inexpensive and relatively easy to replace.

I was thinking that if broken, they might inhibit actuation.

 

If it is stuck in 4x4 and the light stays on, my guess is something in the transfer case?

but yeah, start with the simpler things first. Check the axles first

 

If it does end up being the axles, the best place to get them is Toyota but NAPA has good quality axles - cheaper with lifetime warranties. They aren’t too hard to change if you have the tools. One side took me about 45-ish minutes following this thread here: https://www.tacomaworld.com/threads/how-to-change-a-cv-axle-on-an-01-04-add-tacoma.21192/

However it sounds like the actuator in the transfer case that’s not allowing you to switch back. When you push the button, do you hear a slight buzz? You can hear the actuator if you roll your windows down.

 

I will check for the actuator noise tomorrow. I am away from my truck for the rest of the weekend.

Thanks for the tip on NAPA axle shafts if I need them.

 

With the sparse info you have spread out, I have gathered that you have a 2003 4x4 v6 with the "2-4 Select" push-button transfer case shifter and not the J-stick.

Knowing this, I am leaning towards @DustStorm4x4 's conclusion that it's the actuator, but I believe that it's the one in the front diff, not the transfer case.
"engaging 4wd while my tires were spinning" tells me that you just pushed the button and didn't shift the transfer case to/from LO to HIGH. The only mechanical movement in this case is that the front differential "ADD" Auto-disconnecting differential engages the sleeve that connects the CVs to the differential.

So in this case, several things could have happened - it engaged so quickly with the tires spinning that the quick transfer of speed from the rear driveline to the front stripped the ends of the CVs on the front inside the differential.
More likely, I think the fork that slides the sleeve back and forth is possibly bound up from that quick change of rotational speeds and now is actually stuck in 4x4.

Good luck, report back.

 

Also, those with the 2-4 Select switch transfer case shifter (like me), a fun road trip trick on your passengers is to press the button while going over 60 mph and then start screaming when the truck starts beeping very loudly (this is what happens when you press the button over 60mph - the 4WD ECU prevents the actual shifting and just beeps).

 

If you end up needing a new front diff, @Okiyota has one for sale.

But I'm confused now because another post from you states you have a manual transmission, which is 3.91 gearing.

 

JasonLee, you are correct, 2003 4x4 v6 with the "2-4 Select" push-button transfer case shifter. My older posts are from my previous Taco, which had a 4cyl MT.

I think your hypothesis about the fork is most plausible. I should be able to check 2WD vs 4WD tomorrow and check the axle shafts for play tomorrow.

 

Here's some more reading that may be helpful, @dcubed http://www.off-road.com/trucks-4x4/tech/the-automatic-disconnecting-differential-system-19259.html

*edit* this one has better photos:
http://www.4x4wire.com/toyota/tech/add/

 

JasonLee, very informative links. If my fork is bound up, should I assume that it is damaged or that the sleeve is damaged? If so, can I assume that I need a new front diff or might it be repairable? Is diff removal/replacement a PITA?

I do all my own work up to, and including, engine changes, so I can handle anything. However, in the winter without a heated garage and no spare vehicle, I may have to pay someone to do the work

 

@dcubed Sounds like you have similar experience that I do. I would at least remove the skid plate, remove the electronic actuator that is connected to the fork and look inside there. Maybe it will be obvious, maybe it won't.

With the actuator removed from the diff, if you can support it and keep it plugged in, I would try and cycle the 4WD button to see if the electric motor/solenoid still works. If it doesn't move when it's outside of the diff, it's likely that.

Past that, it's up to you how far you go. I'm in a similar boat - winter and no garage, no spare vehicle. You could remove the CVs, remove the front diff and front driveshaft and then have it out of the truck to work on and still have a functioning 2WD truck...

 

How hard is it to pull the front diff?

 

I’d also be inclined to say it’s he actuator, the same thing happened to my 1 ton dodge, big clunk and it engaged for a second but the actuator was stuck disengaged rather than engaged.

 

The whole diff will be a pain. You'll need to also remove the CVs if you want to drive as you can't let them just dangle around.

To remove the CVs, you need to:
1) Remove wheels
2) Remove the dust cap on the hub
3) Remove cotter pin, lock nut, and 35mm nut on the end of the CV
4) Remove remove either the upper or lower ball joint to tilt the spindle/steering knuckle out away enough to let the CV slide out of the hub
5) With a pry bar, stick it in the right spot and pop them out of the front diff (if you didn't drain the oil yet, some will come out)

...

So, I'd just remove the electronic actuator for now and test that. Go from there.

 

I got home too late tonight to remove the actuator, but I did find that the truck is certainly in 2WD and the 4WD indicator light is off. This is a little strange since the 4WD light was stuck on when I parked it yesterday morning. Toggling the 4WD (ADD) button does nothing, no noise and no 4WD light.

I assume that, at the very least, the actuator is bad. I will plan to remove and replace it. I only hope that nothing else (axle shafts, sleeve, differential shafts) is damaged or broken.

 

Should be easy to tell what's stuck without pulling anything apart. Jack all 4 wheels and put in neutral. Rotate one rear and hold the other. The rear shaft should turn if the front shaft turns the tcase is stuck. (They work the same as the manual shift ones just with an actuator) if front shaft doesn turn. Turn the right wheel while holding the left. If the front shaft turns it's the ADD that's stuck engaged.

It doesn't tell you wether it's the actuator or the fork but beats the hell out of starting in the wrong spot.

 

Stm82, thanks for the tip. Since the truck is in 2WD and the button in the cab does nothing, wouldn't it be one of three things? Either 1. the actuator is stuck in 2WD (fork biased towards passenger side), 2. the fork is broken or 3. the sleeves or shafts are stripped or broken?

It seems that 1. is the most likely since the button produces no noise (buzzing or click) and the 4WD light does not come on.

What switch or switches allow the 4WD indicator light to come on? Does each actuator have a switch in it that senses movement, or is there only one switch? I would think that there would at least be a switch in the differential actuator that would sense the fork position and confirm that the axle shafts were engaged.

 

Your first post said the light was always on regardless of the position of the button?

I know there is a switch in the tcase but I can't remember if there is one in the dif.( more than likely there is.) If no light it won't shift in on one of the two. I think the tcase goes first and when it switch is activated the ADD activates. (I don't have much experience with the circuits but a manual shift like mine would have to see the tcase be for the ADD goes) so no noise start at tcase