How To Trouble Shoot 4x4 Actuator

anyone ever tried accessing this spring loaded wait mechanism? I am thinking this could be my culprit… maybe save myself a few hundred bucks

 

that’s never been a problem. It’s part of the worm wheel.

 

You can access it but I don't know how repairable it would be.

Here's a schematic drawing and picture of the contacts of the ADD Actuator from my thread on the 4wd system.

 

Unfortunately I dont have any good pictures of the spring mechanism. But its just a really big clock spring under the gear. As @6 gearT444E said Ive never read about that being an issue and doubt it ever would be.

It sounds to me like you have water in the front diff. IIRC some oil drains out when you pull the ADD, but not a ton. I would definitely recommend you get that drain plug out (have a new plug on hand, or upgrade to the Lexus drain plug part # 90341-24016) and do a full flush of the old oil. Hopefully the oil did its job and protected the internals for the most part. The fact that you can move the sleeve by hand is a good thing.

 

So the drain plug came out with cold chisel, took maybe 5 minutes (between the fluid loss from yesterday and today it added up to pretty much 1.6 quarts). Refilled the diff but the ADD is functioning just as before. When I turn the switch the transfer case locks up, I hear the ECU click but the light keeps flashing green and the front propeller shaft is engaged.
I am in the process of getting the broken “new” ADD either refunded or exchanged so have to wait for that to get here now I guess.
As for the water in the diff, I dont know if thats the case cause I didnt see much if any water when I drained it. I was on a bit of a slope when I took the ADD out yesterday so that might explain why more than usual amount came out.
Can the timing between the actuators be an issue? I swear these trucks have a mind of their own sometimes.

 

Shouldn't be, the transfer case actuator can be timed incorrectly in relation to the shift fork in the transfer case and I'm not sure if the ADD can be mis-timed internally if it's ever been taken apart or not.

I have all the shift sequences and limit switch voltages in my thread below but since you said it worked a few times and quit and I'd bet it's just bad.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Thanks! Yes I have seen that write up by you and been reading this thread religiously before I took on any of this. This is my first Taco and more of a hunting vehicle than off roading so I am really hoping to get it going reliably for October as we drew again, back to back years, for a goat hunt in the Rockies and the terrain was pretty terrible last year.

 

I did this with much frustration on that one bolt. Did not fix so now I'm going to replace the sensors on the transfer case. Lol, fingers crossed. This thread was awesome tho!

 

Well I am happy to report that after buying the ADD from the dealership it now engages the 4wd like butter. Gave the front diff some extra love too and splurged on some royal purple.

now my battle with ZN automotive to return their broken and non functioning ADD.

off to doing some more maintenance. Gotta get these leaf springs to stop squeaking now and install the ECGS bushing. thanks everyone for their help here, really made this fix easy.

 

Thanks for this info. Hope to not need it someday.

 

Luckily no problem so far but was wondering if any knows the vacuum tubing internal diameter that connects to the transfer case actuator.

I hear it can become brittle /crack and let water in and is one of the prime sources of failure. Want to add this to my check list when i am under the truck greasing the U-joints and might even just replace it with some thin wall high temp silicone hose to fix it once and for all.. Looking at the photo's of the front ADD some of them look like water got in there as well?? Anyone notice if the same issue with the vent tube hose happens here like the rear actuator?

 

There is a ton of very useful and detailed information here on how to diagnose issues with the 4X4 actuator and it has confirmed that if you know what your doing you can indeed repair/replace it without having to take the transfer case out and apart saving mucho $$$

So my question is. If you know the old actuator is bad , can you just do the following with a new actuator

1)Remove the triangular cover on the old Actuator
2)remove the gear that engages the shift fork
3)Remove the actuator leaving shift fork still in transfer case
4)Tap or nudge the shift fork into the case till it hits the last detent position (2H)
5)Remove gear and shaft from new actuator
6)Install new Actuator
7)Reinstall gear and cover plate and thats it??

All this presumes that a new actuator is already set in the 2H position.

 

Yes you can do it that way (most people do), getting the timing correct can be tricky (it may take several tries to get it right).
See also: https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/
Contact postilions

 

Are the brand new actuators already in 2H position?? And the design with the shaft being rotated by a worm gear it should not be able to move out of that position accidentally.
If so and the shaft is in the 2H detent then what would be off? I would expect that as long as the gear that moves the shaft can be reinstalled without anything but the smallest movement of the shaft then it would be ready to go.
Actuator in 2H and shaft in 2h detent position ?? And if any adjustment is needed I would expect it could be accomplished by removing the gear and adjusting the shaft by at most 1 tooth further out or in and then reinstalling the gear???

I am hoping that by replacing the culprit rubber vent tube there I never have to worry about the actuator but like to be well prepared should I actually need to tackle this thing...

 

I'm not sure what position they are shipped in, it doesn't really matter since it has to be disassembled anyway.
As long as the contacts line up with the position the transfer case is in it should work but like I said it may take a few tries to get that right.

 

If its shipped in the 2H position it wouldn't need to be disassembled (except for the gear that moves the shaft) . The shaft and the timing should be correct. Even if its in 4H or 4LO the positions of the shaft and contacts should be correct. I cant see them selling it so that it has to be taken apart.

I gather when toyota does the repair with the transfer case apart they just install it as is and then attach the shift forks to the new shaft.

Anyone buy a new actuator and can answer?

 

I'm not sure why the Toyota transfer cases are set up that way, they are the only ones I know of that you are supposed to disassemble the transfer case to change the actuator.
In any case as long as the contacts on the gear match (see the image I posted above) the position the transfer case is in when you put it together it should work.

 

As far as these actuators are concerned I am an armchair mechanic as the saying goes since I have never yet worked on one. I have rebuild engines and manual transmissions so would consider myself mechanically inclined.
There is a wealth of diagnostic info here and am just hoping I wont have to need it if I was to go with a new one. I just watched a very long time lapse replacement of one of the two shaft actuators on a Tundra by a toyota mechanic in the shop. They did remove and take apart the transfer case. And they then removed the shift fork and shafts by removing old actuator. When it came to the actuator they just bolted a new one on and then reattached the shift forks to the new shafts and put it all back together indicating that the actuator was pre-timed and ready to go as is.
Does this apply to the Tacoma , i hope so.. If not i know where to go to get excellent directions on timing and thanks to all who have contributed to this thread.

Wish I had and actual shop manual so i could answer this question for sure...

 

Yea I've yet to have to replace one on a Toyota either although I did do quite alot of research on the electrical and control side of the system when putting together the help thread I linked to above.

Yea the Tundra uses basically the same transfer case as the Tacoma just a heavier duty version so the shop manual procedure would be mostly the same.

I know I'm not splitting a transfer case to change the actuator when it can be done the other way even if it takes me a few tries to get the timing right.

 

Think I know how to answer the question. Using all the electronic diagnostic steps you have posted you would be able to tell based on voltage on the various pins if a new actuator was indeed in the 2H position (or 4H or 4LO)
If you then installed it on a shift shaft that is in the 2H detent position (or 4H or 4LO) that should do the trick I would think?