4wd actuator hell

Hi. I am new here so im sorry if im supposed to find a relevant thread and tack this on to that or if its normal to start a new one or what.

I have read ALL the threads (at least it feels like it) about the whole gamut of 4wd / tcase actuator / add actuator problems and solutions. Here's what I know.

My add is toast. Took it off, opened it up, water everywhere. Cool fine ill get a new one, extend the breather hose, redo the gasket etc etc.

My tcas actuator looks mint. Made sure it was all times correctly, put it back on.

I took it to Toyota for a diagnostic because I wanted to make sure that the add was my only problem before I spend 300 bucks on a part when I got other problems elsewhere. They get back to me and say its the tcase actuator and its 3 grand (lol nah I'm good bro). I pressed them a little bit because...

1. Why didn't you say my add is also broken because it is...
2. What do you mean my tcase actuator is broken? what test did u actually do?

He said something about the add being dependant on the tcase and so his test showed a fault in the tcase actuator wiring... something something 2 pins being shorted and if that's whats showing up on the test they stop there before going further onto testing the add because its a mute point without the tcase actuator being fixed something something gobbly guk.

So here's my question.. does anyone know what he's talking about? should I just get a new add and hope buddy was full of bs? Is there a way I can replicate his electrical testing? He definitely didn't take any of the actuators off so I'm assuming he arrived to his conclusion based solely on an OBD reading. Can anyone tell me what the hell I'm looking for on an obd that is related to these types of issues?

 

I had a severe tcase actuator issue back on my 2016 (ripped it off while traveling Lockhart Basin Rd). Here is what I recall from testing and fixing my problem on my own:

1) You flip the switch in the cab. 2) This then triggers movement in the tcase actuator. 3) Once that happens the add is then commanded to connect the front axles.

Those are the steps that the system goes through, one at a time (not all at once). Reverse that for going back into 2wd (switch, then tcase, then add unlocks).

If he is saying that he can't get the tcase actuator to do anything then he can't check the system deeper, because the tcase actuator comes right after flipping the switch on the dash, and before the add.

How did you get water into your add? I have submerged my truck over the hood in river crossings and never had mine fill up.

Timing the tcase actuator can be a pain in the ass, you sure you reassembled it correctly?

 

Hey thanks for the reply. So I don't remember exactly where the breathers are but I remember digging into this a bit and a guy on YouTube showed where the add breather tube is. Kinda by the alternator if I remember. It's a common problem on these forums and doesn't seem to effect the transfer case as bad (maybe because that breather is in a better spot?)

I physically removed my tcase actuator and it didn't have a spec of dust in it.

The process for switching from 2 to 4 is as you described but according to the internet It seems like the process to go back to 2 actually goes in the same order. Transfer case first and then add.

I just don't really trust that there is anything wrong with the transfer case to be honest but I don't know why he would be lying. Would a timing error in the transfer case actuator cause his diagnostic to go off? Im just bad with the electrical part of this. I understand both of the parts physically/ mechanically.

 

OP, first off, good luck with the troubleshooting, and next there is a thread and member here who knows the Tacoma 4WD system very well.

I believe it is @BigWhiteTRD that was posting in that thread, can’t seem to find the thread.

 

If the dealer said they diagnosed a short, I'd suggest opening up the wiring hsrness, working from the tcase actuator on up to see there is any visible damage anywhere in the run.

Dosconnect and inspect the plug first, lol. And check the hwrness on the tcase side as well.

I agree that the dealer is pushing for a parts change, not a diagnosis. But as mr e30 says, the steps to connect everything happen sequentially, so if theres a short somewhere invoving the tcase actuator, theyre not going to progress any further than step 1 due to diagnostic time (wiring insoection) being a tedious time cost. (Cue: "i'm not paying 12 hrs labor to replace a shorted wire")

 

A timing error will DEFINITELY throw his diagnostic off.

The 4wd ECU will check the feedback, and it needs to match the expected values, as reported by techstream.
https://www.tacomaworld.com/threads/4wd-actuator-troubleshooting-transfer-case-and-add.578262/

A standard OBD output wont help you here. It requires techstream or some equivalent.

 

okay here me out.. Im kinda at the point where im thinking I might fabricate my own mechanical solution. Im thinking I could do a simple lever straight through my center console, hinging "somewhere" and welding straight to the rod sticking out of the tcase. I would then have to make some kind of boot coming off the tcase where the rod is and another one sealing the levers passage into the cabin but ya... I know there are old toyota tcase shift levers and units and such but they seem like they need a more dedicated space to exist around the shifter so im thinking of just mcgyvering it. For the ADD im thinking of running a quasi bicycle brake line and running it to the add actuator. I will reuse the fork and metal housing but fab my own lever and plastic housing to interface with that fork. I would probably have to use like two separate cables. One for pulling the fork to the right and one for pulling it to the left because i have no clue how to engineer a mechanism to translate pulling 1 cable to switching a lever back and fourth. I would have it tensioned so that when one stop is pulled it locks and then to switch back i release that stop and then there is enough slack to pull the other stop corresponding to the other fork position and vice versa.

Idk Idk it sounds crazy but it makes sense in my head.

Would I need to reprogram my ecu to lke forget about the 4wd system to make sure my truck isnt spracking out because these components are now gone? Is this possible???

 

If I had to gamble a guess, what you described above is not possible.

The 'shifting' of the 4wd system does more than just move that shaft in and out of the tcase. It has positioning sensors/mechanisms inside of the actuator that disable VSC, ABS, etc.

You will likely have a permanent '2wd-4wd change failure' error in your gauge cluster as well.

And that seems like a very convoluted workaround compared to properly diagnosing and repairing the OEM system.

I too got frustrated when I had my 4wd issue, but I just kept plugging away, and after a few days I had it all worked out. IMO, having that entire system function as it was intended by Toyota is the only way I would want it to function.

 

the man , all knowing wizard @gearcruncher can diagnose the problem with a solution

 

Properly retiming the t-case actuator is a total B* on the 3rd gen from what I recall the one time I did it

If your ADD is known bad, and you have to replace it anyway, why not do so now and see what happens? If 4x4 still doesn't work next logical step is the T-case timing

 

And on a 2020 truck to boot? MacGyvering something like that should be reserved as a last resort if 4wd functionality was a matter of life and death if you were stuck in a remote location and needed 4wd to work temporarily to get you out safely. To consider that as a solution on a 3-4 year old truck is insane, lol.

 

honestly ya that would be a little crazy. I feel like maybe one day when I have another daily I can look into a bulletproof analog shifting solution. Probably just going to order the dang part and pray to the Toyota gods that that's my only problem.

 

It sounds like the solution you are looking for is a manual case swap out of an auto fj cruiser paired with an add delete live axle from an AWD fj. I just finished mine up. As far as the actuators go, I still have them plugged in to maintain 4x traction control on icy roads, but all gear shifting is with twin sticks. I removed the shift rods/forks from the actuators, spent hours getting them clocked correctly, sealed them up and zip tied in safe locations. Pretty big job but straightforward and totally worth not having the damn truck beep at me every time I want to try to change gears.

 

Since you have gone all manual activation, did you try just removing the 4X4 ECU module behind the glove box. It is my understanding the 4x4 traction control accomplished with the ABS controller not the 4x4 ECU module. If you have the Toyota rear diff lock ignore my observation as that still does require the 4x4 ECU module.

 

In my research it seams that while ABS/Traction aren’t controlled by the 4x ecu, they do require feedback from the system and won’t work with the ecu disconnected, or even a disco’ed actuator, so I left everything connected. I have a sport and manual lockers so I don’t need the ecu for elocker activation. Basically now, if I’m off-road I just shift manually and use the trac off long press. On slippery highways I shift manually, then shift with the stock dial to get 4x traction features.

 

I have a feeling that would not work. The Skid control ECU does all of that work, but it's definitely looking for inputs from all the other ECUs. Just having the e-locker unplugged when you have the "with e-locker" 4WD ECU installed shuts down a whole bunch of traction modes. Of course, the 4WD ECU is the one reporting that and telling the skid control ECU to shut those traction modes down, so maybe the skid control ECU would not do that if the 4WD ECU was removed completely, but I'd be surprised if there wasn't a catch somewhere.

What I don't know is if the skid control ECU is programmed differently depending on whether or not the vehicle is 4WD. Maybe simply unplugging the 4WD ECU would default into the vehicle being like a 2WD, but I really don't know. I doubt it though, that seems too easy. I suppose somebody could yank the glove box and try.

 

I'll disconnect my 4x4 Module today and see what it does in the way of any codes. Glove box is already removed.

 

Fj swap and call it a day. The only thing electrical in my driveline still is the factory rear locker. Mechanical > electrical

 

I agree with you, though it's a bit harder to do that swap and make everything happy in a 3rd gen vs a 2nd gen. For example, right off the bat you'll lose indicator lights because those are communicated over Canbus by the 4WD ECU, there is no wiring on the instrument cluster that you can manipulate to make the lights work when the manual t-case is shifted.

Keeping traction modes can also be difficult. So can the locker, if equipped. There's a lot more local network communication on the 3rd gen than 2nd, unfortunately. You can of course still just slap in the manual transfer case for sure, but may lose some functionality. That's why people end up with spoofer harnesses and keep the stock knob and sometimes even the ADD with a switch harness for it so they can maintain function while having the manual case. They still end up keeping all their functionality, but it's not as simple to use as a stock vehicle with a manual t-case that you simply shift and don't think about.


I'm editing this because what I said originally is not 100% true after more research:

The ADD and transfer case can both be spoofed, electrically, using relays. If done properly, the 4WD ECU will think both are still there and functioning. It takes 6 relays total to spoof both: 5 for t-case, 1 for ADD. See my development thread for details:

3rd Gen Spoofer Development for ADD and Transfer Case Actuators | Tacoma World

The unfortunate part is the physical hindrances still exist. On a manual transmission, you still need to do grinding to the transmission housing and the transfer case shift rods. You also still need to bend the shifters for clearance and possibly use a short throw shifter on the transmission.

On automatic transmissions, you have to do a nasty hack job on the center console which is not exactly easy to make look presentable (IMO).

However, if you can get the transfer case physically installed to your satisfaction, then electrically, it is totally possible to make the truck happy with the change, which is great.

 

YES. There were all kinds of indications and codes with the 4x4 ECU Module disconnected.
"Pre-Collision System Malfunction"
"ABS Check Anti-lock Brake System"
Dash ABS light lit
Dash Slip Indicator lit
PCS Warning light lit

Cruise control was inoperatable.
Lane Departure worked just fine.

Codes:
U0114
U1117
B1579
C1A50

So, this means when I get rid of my OEM E-Locker I will have to put a resistor on the wires to fake the 4x4 ECU into believing it is still connected. When I regear (5.29) I will put in ARBs both front and rear.