Well, TFL got word back from Toyota. The ADD failed in the front axle. No word on why yet. Apparently, Toyota engineers are aware and are looking into it now. Outside of it being just a bad part, there are two ways to look at it: The ADD did its job and failed like a "fuse" preventing greater damage to an axle or the diff itself. Or, the ADD can be considered a very weak link in the chain of components. I'm leaning more to the latter considering where and how it failed. Sounds like they put a 5A fuse on a 10A circuit.....
TFL just broke their Tacoma
- Thread starter Fightnfire
- Start date
Fightnfire
Moderator
I'll have to watch the video but I feel like Toyota made a big deal about that ADD in the Tacoma maybe new type or in a new location?
Beninbeta
Well-known member
I don't think it's new. I would also say that like the Chevy engine issue, TFL is the only person I have seen report this issue anywhere so far. There only a couple thousand of them out and about, but every 4WD Tacoma one the road has the this same setup. So if it's wide spread, there will be more people reporting this. It'll be interesting to follow though.
I know The Car Car Nut talks about it in this extremely in-depth review of the Tacoma from a service professional perspective. Grab a pot of coffee or whatever though. It's long!
I know The Car Car Nut talks about it in this extremely in-depth review of the Tacoma from a service professional perspective. Grab a pot of coffee or whatever though. It's long!
Not too much detail. Nothing physically broken when on the lift, then the rollers confirmed the front shaft was spinning so the problem was the front diff somewhere. Then the close with the news from the dealer that it was the ADD and Toyota was all over it. Hopefully, they get more details and some explanation from Toyota. I'm sure the failed part was whisked away in a briefcase handcuffed to an intern's wrist heading back to HQ.
Fightnfire
Moderator
That's a good explanation of the ADD (Automatic disconnecting differential) if you're interested, I was positive I had heard that the system used in the 2024 was slightly different than the previous gen but I'm not finding it googling. I think it was mentioned in one of the ealry release videos or Hawaii with Sheldon. It doesn't really matter but the ADD is a somewhat commone issue with the Tacoma. Basically, if something goes wrong with 4WD engagement or disengagement this is one of the leading causes.
Manufacturers all handle this differently, that is the move from manual locking hubs to electronic 4WD systems.
Tacoma's and Toyota 4WD vehicles have a history of struggling to engage or disengage 4WD, especially 4L the actuator in the ADD is the typical problem:
"There are two switches that must be in the closed position for the 4WD light to come on. The first switch is controlled by the position of the transfer case shift lever. The second light is on the ADD actuator and it turns on after the sleeve has moved into the right (locked) position."
"When the transfer case gear shift is shifted into 4WD, the ADD system is actuated by the operation of the ADD solenoids located under the hood on the passenger side wheelwell."
That's what I thought had changed, I remember someone noticing that isn't there anymore or looks different on the 2024. It could have been a limited which has a FT 4WD system and thus wouldn't have the ADD unit.
I would want to ask Sheldon to talk about this component specifically. Was it changed? If so, why or why not?
I disagree with the "fuse" aspect and I still haven't watched the video. I mean I get what they're saying but it sounds a little like a cop out to a system that is known to cause problems with Toyota. If I'm stranded because the ADD broke I don't know if I care that it saved another component. What's the stress load of the ADD breaking vs. a diff or something else? Those are Sheldon questions I guess.
For what it's worth Jeep and Bronco use a FAD, front axle disconnect. There is some decent articles out there about the differences and how the disconnect is handled. (FAD is also seen as a "weak spot" on the Jeep, not sure about it's reliability as I'm not on any jeep wave forums)
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I thought the main issue with the previous ADD was water infiltration causing corrosion of the internals. My son is the big Taco guy and he said that's the problem most owners had.
Fightnfire
Moderator
Correct, it isn't/wasn't a great design and was really finicky. Water, dirt, mud and snow buildup all caused it issues, and If it wasn't redesigned ....it's handling soooooo much more torque now, down low.
Yeah this failure seemed more physical, plus I don't think they've had it long enough for corrosion to factor in. But I will say this, being able to drive out of the woods like TFL did was damn lucky. A damaged xfer case or a locked-up front diff would have really sucked. Kinda like blowing your locking hubs of days past, I'd rather that than an axle. I've experienced both and I'll take the hub any day, all day.Correct, it isn't/wasn't a great design and was really finicky. Water, dirt, mud and snow buildup all caused it issues, and If it wasn't redesigned ....it's handling soooooo much more torque now, down low.
Beninbeta
Well-known member
I would agree with this. As a hopefully, soon to be new owner, I'd rather at least still be able to drive the truck and maybe get back home. Even if then the replacement part is more robust at that point. That being said, if this is widespread they need to recall the trucks or I guess hold them another X amount of time and fix them in the port.
Fightnfire
Moderator
Unfortunately it's not a fix they can really do, it's how they design their front axle to work and the "cornerstone" of the Toyota 4WD system. It would take a redesign of the entire ADD system to imrpove. If it is truly a straight carry over from the previous gens.. hmmm that's an oversight on the engineering team as they're known to cause issues. It was the weak spot on the 2nd and 3rd gens.
I don't want to make it sound like they fail constantly, more so that when there was an issue with the 4WD system this was the key player usually.
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I'm curious about what force was stressing the driveline at the time of the break. From the video he had turned off crawl control, but was traction control still active? The front wheel didn't look like it was freely spinning on the ice (spin yes, but intermittent), there was no lurch forward when the snap occurred, and the way the front end dropped when whatever broke gave way seems to indicate there was a lot of torque involved that wasn't attributable to one or both of the tires finding purchase after spinning through the ice. Could the root cause be traction control that Toyota has configured to be a bit too aggressive? Or should the driveline be able to handle full braking at full torque in 4lo regardless?
Apologies in advance if this is a stupid line of thought. I'm no 4wd mechanical expert.
Apologies in advance if this is a stupid line of thought. I'm no 4wd mechanical expert.
Fightnfire
Moderator
Can't answer it all but the intermittent wheel spinning was the traction control systems trying to find grip and braking wheels to stop the spin to send power elsewhere. The ADD broke, that they said... but where and how? The actuator or the axle sheath itself? Two very different things..and possible concerns.
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Which is why I never like spinning tires in those situations. Deep snow or mud is one thing but where they were at, you have no idea when a tire will grab and that sudden stoppage being transferred to the drivetrain.
I do know that the traction control in the Taco is de-energized when the rear locker is engaged, which they said was on at the time. And that appears to be true as both rears were spinning together. I am not sure if the new 4wd system with does anything else like Trac does but I guess we'll find out eventually.
Seems to me the ADD system did its job and broke instead of a more expensive part. The question is going to be should the ADD be strengthened or is this just a weird coincidence? I doubt major recall since the part isn't exactly new.
I can imagine a hundred people doing the same thing that TFL did and 99 of them having no problems. It isn't like Toyota didn't test the truck in this fashion. They did and they torture tested it in worse conditions.
Like I said earlier, things happen. Parts break. Like @Fightnfire said Jeeps have a similar Achilles' heel.
For my money, I'd bet this will turn into much ado about nothing in 6 months like the waste gate issue.
I can imagine a hundred people doing the same thing that TFL did and 99 of them having no problems. It isn't like Toyota didn't test the truck in this fashion. They did and they torture tested it in worse conditions.
Like I said earlier, things happen. Parts break. Like @Fightnfire said Jeeps have a similar Achilles' heel.
For my money, I'd bet this will turn into much ado about nothing in 6 months like the waste gate issue.
True. Hard to see this going anywhere unless they realize the current design just can't handle the new TQ numbers. But in the end, probably just a single bad part that unfortunately for Toyota, exploded on YT in relatively tame spot for all to see.
Not quite as bad as the Musk shot at the window but not fun for the PR team regardless....lol
Not quite as bad as the Musk shot at the window but not fun for the PR team regardless....lol
Beninbeta
Well-known member
@testerdahl I agree, this is likely a one off and the Toyota tested these everywhere. The one thing that got me thinking in the video though was how they drive off road. Being less experienced in this area, I reached out one of the off road instructors they had at the drive event and we've been going back and forth about maybe doing a lesson. During our conversations he said the number one thing to learn is driving with two feet, and that makes sense. It doesn't seem like TFL, beyond maybe Tommy, does this. Which is why the fly up an obstacle and hard stop rather than slow and continue. I suspect if they used the method, nothing would have broken either. Not an excuse for it breaking. How many of you use the 2 foot method. In a place like Wisconsin there's probably no need for that, but Utah, Colorado, Arizona, PNW and a few others I can see that being a benefit. One of the people I used to work with drove that way everywhere and I always intrigued.
I've done some two-feet driving, however, that idea is going away. Why? A few of the new trucks have incorporated off-road mode allowing for one pedal driving. I know the Chevy Silverado 1500 has terrain mode which is really one pedal driving and the Colorado has it as well. It takes away the need for using the brake.
I still wonder if Crawl Control would have handled that obstacle better. He switched it off pretty fast, but that system is meant to replace two-pedal driving in that scenario.
Agreed. Modern systems are totally different. It was like when we got used to ABS. "Don't pump, nail the brake and let the system function as designed." Now, my old 84 CJ? Yeah that takes three feet to drive well sometimes.