Thanks a ton! I think the tech actually performed these tests - based on him being able to say whether the ADD motor works or does not. But I was never given a detailed result—they probably found it more economical to just replace the ADD.

We know the motor works is what I'm trying to tell you. Intermittently. Motors don't work just intermittently. Failures in the circuit cause intermittent motor operation. He said there was communication signal problem between modules. Which could mean anything that could go wrong. Covering his ass.. the diagnosistic above he didn't do. These diagnostics check the internal limit switches, ADD detection switch inside the module are functioning/engaging properly. But f_ck if your warranty covers it get a new one again and again. Keep the old one this time!

Yeah, I hear ya. I don’t wanna replace the functioning ADD-I just don’t want it to fail on the Rubicon or in the middle of Nevada desert. I’m taking the truck to the dealer on Monday, and I just hope there’s service rep that was decent. The first time I took it to the dealer, another service rep told me the 4wd failure won’t be covered under warranty because I had aftermarket skid plates..made me learn quickly that guys who work at the dealership know nothing about cars.

Hilarious. Aftermarket skid completely ****ed your 4wd, that's a new one.. request all your service records on this issue if you don't have them already. Talk to the shop manager only from now on. They may not know much as you said but also they are also assuming you don't know jack sh1t.. doing the same thing over and over again expecting different results is the definition of insanity.. make sure you have all documentation from when you first had this issue. If you do have an accident or wanna get real slick and pull a scam on these c0ck suckers 😉😉 you should be covered with all documentation. This is a safety hazard as far as I'm concerned and shouldn't even be on the road.

I appreciate you being being mad about this too. I think to me this is the issue that’ll make a break whether I get a toyota 4x4 again.

PS, based on research, many people have the 2WD to 4WD malfunction when the prongs within the ADD motor lose connection. People just solder them to be safe. But it doesn’t make sense in my case because all I need to do is to restart the engine and the code clears.

You keep saying that the terminal ends break... I honestly can't recall seeing that? You have pictures, I'd be curious to see what you mean.

As for the issue, I am leaning on either an issue in the actual electrical circuit causing a hiccup or some sort of odd mechanical issue inside of the differential jamming up the mechanism occasionally. I'd start with the electrical side of things since that's the easiest to test and go from there. It doesn't seem like an ECU issue to me, it's still a possibility; but it seems odd to me that it would occur intermittently and then outright fail (like your two prior situations).

I don’t think terminal ends is currently the issue because the current issue fixes itself by restarting the vehicle. I do think that the terminal ends could have been the cause of the blinking 4x4 sign that was “fixed” with a mallet. Strikes could have made the ends touch.

There are many videos talking about this issue:

Toyota Tacoma | No 4wd Fix | 2wd / 4wd Mode Malfunction Fix | (2017 Tacoma) - YouTube

Toyota Tacoma front axle 4x4 actuator (ADD) fix - YouTube

Toyota Tacoma's 4x4 Issues | 2wd to 4wd change failure How To Fix - YouTube

Ah I see what they mean, it's been a bit since I took one apart (last 3-4 I did in the past few years have been warranty so had to send the parts back). They basically do them like large power mirror motors, "drop-in" style; I suppose I could see them developing poor contact over some time due mainly to moisture intrusion and carboning. Though the weird thing in those videos and other pictures of the ADD being torn apart is there's no real fixture/support for the contacts... in power mirrors there's a sort of plastic cradle/support for the contacts so they stay fairly well seated; the contacts are also springy so they press against the motor ends to maintain contact.

In any case, it's likely not the issue we're dealing with. I'm still leaning on something funky going on electrically in terms of signaling/commanding the system and/or something mechanically interfering with the operation of the ADD and prematurely burning it out.

Speak.

If the dealer doesn’t solve it, I’m happy to show the truck to y’all if you’re on the west coast. I’m doing gears next week and putting a locker in the front, so I’m pretty certain they won’t fix anything under warranty after that

Dirty south Arkansas representing! If they can't solve it how did it get engineered and built. F_ck tarded. Reverse engineering alien spacecrafts no problem. It's their broken truck not your fault. How can they possibly get away with that. Need to get an electrical engineer in there not a technician if he doesn't have the ability to do the job. Have you read your warranty front to back for loopholes or other options? Sounds like an attorney might be helpful but $$$$ expensive. I don't know what to do if they can't resolve it besides do it myself. What a joke.

If I still lived in the Bay Area I'd actually tell you to either schedule with my old dealership and ask for me or just stop by on a weekend and we'll take a quick look. Unfortunately I moved out north to Central Oregon.

Since It’s just electric stuff, maybe I can just grab a multimeter and test it myself if it comes to it. I’ll need to study more on the diagrams you shared.

Well, now the 2WD to 4WD Mode Malfunction warning doesn’t go away (along with blinking 4L and multi terrain select malfunction). Maybe that’ll help when taking it to the dealer tomorrow. Notably, also, the malfunction warning came up again AFTER I put the truck in 4L (constantly testing it now), and it showed 4WD as disengaged even after it engaged when I put it in 4L. Sketchy moment..

Yes sir you can! You'll need long leads or extensions to reach between the add and the 4wd ECU. Maybe alligator clips. Some good kits out there have all the multimeter accessories that make it way easier doing it alone. A test light is my favorite electrical tool. You can diagnose anything electrical with these two simple tools.