Toyota 4wd Reliability?

[BlackWorksInc]

I'm not entirely surprised that they asked you that, from what I understand from some FTS and DSPMs I have talked to when they snap pictures of modified vehicles have mentioned; the engineers don't really think people actually use these vehicles like that.

I actually vaguely recall one of the 5th gen members were a driving force for having the cylinder head oil drain passages adjusted. lol

...

Though, it seems odd to me that they had them just throw a 3rd ADD actuator in it and not do anything else. I would have figured that they'd want some more information/data on the vehicle...

I feel like something has been skipped here...

 

[Jakeepoo3]

I'm not entirely surprised that they asked you that, from what I understand from some FTS and DSPMs I have talked to when they snap pictures of modified vehicles have mentioned; the engineers don't really think people actually use these vehicles like that.

I actually vaguely recall one of the 5th gen members were a driving force for having the cylinder head oil drain passages adjusted. lol

...

Though, it seems odd to me that they had them just throw a 3rd ADD actuator in it and not do anything else. I would have figured that they'd want some more information/data on the vehicle...

I feel like something has been skipped here...

Get the old module!!

 

[bayaz]

I'm not entirely surprised that they asked you that, from what I understand from some FTS and DSPMs I have talked to when they snap pictures of modified vehicles have mentioned; the engineers don't really think people actually use these vehicles like that.

I actually vaguely recall one of the 5th gen members were a driving force for having the cylinder head oil drain passages adjusted. lol

...

Though, it seems odd to me that they had them just throw a 3rd ADD actuator in it and not do anything else. I would have figured that they'd want some more information/data on the vehicle...

I feel like something has been skipped here...

They should be doing more testing today. But based on the circuit testing they did yesterday, it’s the ADD (and not the motor). The dealer said that some off-roading was expected but they were asking if I did anything extreme. In my mind, extreme is doing Chocolate Thunder at the King of Hammers, and no 4runner can do that. But I agree that it’s a silly question because the only way off-roading can affect the ADD is if I slam it into a rock, which hasn’t happened. I generally agree that Toyota does not cater well to its off-road enthusiasts. While Jeep and Ford design off-road-worthy functions into their trucks, Toyota 4x4 is largely just bragging rights for yuppies who engage 4wd once a year when they go skiing in Tahoe.

 

[bayaz]

Get the old module!!

Yes, I will. I wanna test it myself. Do you guys have access to the TAS system? There’s a case number in TAS, so I’m wondering if you’re able to see what Toyota HQ thought about the issue.

 

[Jakeepoo3]

Yes, I will. I wanna test it myself. Do you guys have access to the TAS system? There’s a case number in TAS, so I’m wondering if you’re able to see what Toyota HQ thought about the issue.

I don't know if that's possible but would be interesting to read. The diagnosis says that the front drive shaft was rotating but neither front wheel rotates.. Is this even possible. MANUAL POWER UP FRONT ADD ACTUATOR, AND WAS ABLE TO PUT THE FRONT DIFFERENTIAL IN 4WD. Not sure what he is saying, it's not clear. I'm assuming he manually applied voltage to the module like the diagnosistic I posted for you and got the motor to operate and engage the sleeve into fully functional 4wd. This just proves the the add module is functioning properly right.. he bypassed the circuit that communicates to the module and it works. He didn't test the circuit is what I'm not understand, why??? This is what I feel is being skipped like blackworks said for some odd reason.

 

[bayaz]

I don't know if that's possible but would be interesting to read. The diagnosis says that the front drive shaft was rotating but neither front wheel rotates.. Is this even possible. MANUAL POWER UP FRONT ADD ACTUATOR, AND WAS ABLE TO PUT THE FRONT DIFFERENTIAL IN 4WD. Not sure what he is saying, it's not clear. I'm assuming he manually applied voltage to the module like the diagnosistic I posted for you and got the motor to operate and engage the sleeve into fully functional 4wd. This just proves the the add module is functioning properly right.. he bypassed the circuit that communicates to the module and it works. He didn't test the circuit is what I'm not understand, why??? This is what I feel is being skipped like blackworks said for some odd reason.

I was reassured yesterday that the whole 4wd circuit was being tested this time.

 

[Jakeepoo3]

I was reassured yesterday that the whole 4wd circuit was being tested this time.

Post a screenshot of the diagnostic sheet they're supposed to provide you with. Should show continuity tests between all terminals, ground test, signal values between modules in and out of 4wd. The other diagnostic I posted for you and recommended you familiarize yourself with before going in there. The diagnosis printout will be more reassuring than some worker sheep's word.

 

[bayaz]

Guys, need your help here. The dealer got back to me. Says the cause is a ruptured breather hose. See pics. And they say that Toyota HQ guided them to identity this issue and they say it’s because of a lift. It does not make sense to me because a lift does not lift or drop the front diff. I’m going to see the truck and talk to the tech working on it because it’s Bs. Any suggestions?

 

[bayaz]

I also asked why this didn’t come up last times. I specifically asked the actual tech if there was any water or corrosion in the diff, and he said no. Further, I said the hose wouldn’t be replaced by the tech but they said the tech replaced the breather hose last time. I’m very skeptical. They want $1200 if I wanna fix it. And I need store managers approval to dodge the diagnostic fee.

 

[bayaz]

Just went to the dealer and talked to their master tech. They showed me the ruptured ADD breather hose. It ruptured right around where the soft hose connects to the hard hose next to the front diff breather. I kept pressing the tech to explain to me how the lift could have influenced it since the front diff is stationary, but all I got is that Toyota HQ said this is a known issue related to the lift. I then asked if they taken the ADD apart to confirm if there’s any debris inside the motor and they said they can’t do it because the warranty policy is just to replace it and not disassemble. They’d only disassemble the ADD if I paid for the fix. Honestly, this sounded like a wash.

On the brighter side, I got more information as to circuit testing. The tech did test all the 4wd circuits. Everything worked except for a switch in the ADD. DL1 and DL2. Apparently, if the truck is in 2wd, it should be as follows DL1: On, DL2: Off. when in 4wd it’s in reverse. Well the ADD went in limbo, both DL1 and DL2 are on. This does sound like some water damage. So I’ll be replacing the ADD myself and putting an ARB breather hose that I have.

Any other comments or suggestions welcome. I’ll update when I replace the ADD.

PS: attached is the ADD breather diagram where I highlighted where I got a hole.

 

[Jakeepoo3]

Interesting how their method of dealing with this issue completely changed when you asked for the old module back. We're they even replacing it in the first place..

 

[bayaz]

Interesting how their method of dealing with this issue completely changed when you asked for the old module back. We're they even replacing it in the first place..

Actually they said they can’t provide the old module if it’s replaced under warranty. They claimed that they had to send the old module to Toyota. I’m gonna replace the module myself and put my own breather…if this solves the issue, I’ll be beyond thrilled. The dealer’s master tech said this is the second truck in his career that he’s seen the ADD fail. I just can’t understand how the breather line could have been ruptured. Especially by a lift (possibly by diff drop?). Part of me thinks they might have faked it? Idk.

 

[bayaz]

Here’s what official record says:

)Z-DIAG
DIAGNOSIS
TECH(S): 158
CUSTOMER STATES MODE CHANGE MALFUNCITON WARNING ON REPLACED
CONFIRMED 4L0 LIGHT IS FLASHING, AND MODE SELECTION LIGHT
IS FLASHING. RAISED VEHICLE,
AND INSPECTED. WITH SIFTER IN
4WD THE FRONT DRIVE SHAFT IS SPINNING, BUT NOT THE FRONT
WHEELS. MANUALLY POWERED UP THE FRONT ADD ACTUATOR, AND
CONFIRMED THE FRONT WHEELS ARE NOW SPINNING. CHECKED FRONT
ADD ACTUATOR DL1, AND DL2 AT 4WD ECU WITH SHIFTER IN 2HI.
. BOTH HAVE 12 VOLTS. CREATED TAS CASE,
CASE NUMBER 221370093.
WAS INSTRUCTED TO INSPECT THE VENT HOSE FOR CRACKS OR TEARS.
CONFIRMED VENT HOSE IS TORN, AND IS ALLOWING CONTAMINANTS TO
ENTER THE FRONT DIFFERENTIAL ACTUATOR. RECOMMEND REPLACING
THE FRONT DIFFERENTIAL ACTUATOR, VENT HOSE, AND RECHECK FOR
PROPER OPERATION.
NO CHARGE FOR DIAGNOSTIC ONE TIME GOODWILL.

 

[mbm112]

The frustrating thing about warranty work is that it sometimes doesn’t make sense. It’s very scripted with thousands of combinations of “if this, then that.” Unfortunately sometimes the logic doesn’t add up, but the response has been predetermined by the OEM, so even if there is an alternative method or fix, the dealer can’t go with it because it’s not approved.


Sent from my iPhone using Tapatalk

 

[BlackWorksInc]

I'm sorry to hear that.. only thing I can think of is the line got pinched somehow, but I'm not sure how? But that breather line allowing moisture into the ADD makes some sense, though I'm not sure how fast that corrosion would set in (though all you'd need is the limit switch to act up to cause problems). You can jump the motor pins and/or de-pin the limit switch to "trick" the vehicle, useful for diagnosis. As for the front wheels not spinning, that is because the front differential is open; when the ADD isn't engaged, the path of least resistance is through the disconnected axle shaft.

Unfortunately when it comes to warranty work, parts have to be returned to Toyota; it's just how warranty policy works.

Hopefully this will be the last one you need to replace!

 

[bayaz]

I'm sorry to hear that.. only thing I can think of is the line got pinched somehow, but I'm not sure how? But that breather line allowing moisture into the ADD makes some sense, though I'm not sure how fast that corrosion would set in (though all you'd need is the limit switch to act up to cause problems). You can jump the motor pins and/or de-pin the limit switch to "trick" the vehicle, useful for diagnosis. As for the front wheels not spinning, that is because the front differential is open; when the ADD isn't engaged, the path of least resistance is through the disconnected axle shaft.

Unfortunately when it comes to warranty work, parts have to be returned to Toyota; it's just how warranty policy works.

Hopefully this will be the last one you need to replace!

Yes. Thanks! I started doing more research on the actuator flooding, and it appears pretty common.

Front 4wd actuator POS | Tacoma World

Some guy even went ahead and removed the entire actuator assembly (nifty idea, but then the front diff would be spinning, no?) curious if this would cause wear:

How to: Deleting ADD system | Tacoma World

For now, I ordered the new ADD and will install it myself. I am planning to use Ultra Black as a gasket maker. And then I think I’ll just plug an ARB breather line directly to ADD, skipping the factory breather line that ruptured. The factory line is tucked away so deep against the engine that it’s no surprise that the tech couldn’t identify it as a problem. You just can’t see it unless you pull it out, and why would you pull it out? It still doesn’t make sense to me that a lift would affect it (though I can see the diff drop possibly do the deed, as it tilts the diff and pulls on the breather line, which is pretty tight against a metal line).

Overall, the dealer was very nice to me (assuming they didn’t lie). Spent a lot of time talking to the tech, and even waived the diagnostic charge (albeit after some haggling). The tech showed me the 4wd testing diagrams that you guys were talking about. He popped open the glovebox compartment to access the 4wd circuit).

If anyone has any additional tips or suggestions on replacing the ADD and breather hose, please let me know.

 

[Jakeepoo3]

I hope this was your issue! I'm not going to get excited yet though. Your *diff oil and magnets* could be the one to tell you if the breather hose was actually sucking in moisture and debris or not. Be very observant of things like this. They hold valuable clues and answers. I think there is a check valve on that breather that can get stuck too. I'd have to check it out though, I'm not sure. And whether that hole is before or after the check valve.. May be something you want to look into in more detail

 

[bayaz]

I hope this was your issue! I'm not going to get excited yet though. Your *diff oil and magnets* could be the one to tell you if the breather hose was actually sucking in moisture and debris or not. Be very observant of things like this. They hold valuable clues and answers. I think there is a check valve on that breather that can get stuck too. I'd have to check it out though, I'm not sure. And whether that hole is before or after the check valve.. May be something you want to look into in more detail

I think the diff fluid should be fine unless the seal has failed. The breather hose that’s ruptured leads to the ADD motor. The front diff breather is fine. Very odd, considering the two hoses are attached to each other. But yeah, I’ll take a look at the diff oil

 

[bayaz]

Guys, quick question. Got the new actuator. But the shift fork on the new one is currently in 4wd position, so I can’t mate it to the current 2wd position. I understand I can just connect the actuator to the batter and switch, right? How do I do it?

 

[bayaz]

I figured out how to make the motor run. Connect the bottom two pins to the battery and voila.

Also, I removed and replaced the ADD. The old one actually worked as far as engaging 4x4. But when I cracked it open, it was full of water and corrosion. See pics.

Also, I’m not the only one with this issue. This guy found the culprit: there’s a hose clamp that punctured the breather. Tacoma A.D.D. Diagnostics (4x4 Front Differential Actuator) 3rd Gen 2020 - YouTube