HELP 4x4 wants to fight

Ive been running into some issues with my cool little truck. I have recently done 5.29 gears and arb locker, new clutch, and somwhere along the lines my 4 wheel drive stopped working, ive checked all vac lines and they all check out, plugs are plugged in and ive replaced both actuators and still just left with a flashing ligh.

Today i pulled my diff actuator apart, the motor is great and bench tested fine as i would expect from a brand new part, and T-case is engaging, front drive shaft is spinning but the diff actuator will not shift the collar into place. I manually shifted it and it moves freely with no binding, but for some reason i can not get it to work all together,

 

I dont know if it will help your situation but I had a problem on my last truck where it wouldn't engage sometimes and if I turned the truck off, Switched it to 4hi, and then turn the truck on it would go into 4wd just fine. I never tried to fix the problem. I only had to do that a few times ever. I feel like it just sticks sometimes. Your truck looks awesome by the way

 

thank you, yeah ive tried the little tricks these trucks need but it seems to be a gremlin instead, wether its vacuum or electric something is not actuating the front diff

 

Hmm. Strange. Well I wish you best of luck fixing it.

 

FWIW there is no part of our 4wd system that is vacuum actuated. The little hoses you're seeing are breathers. Good luck on the hunt.

 

Damn I’ve had this things sense 2016 and always thought it ran vacuum, thanks for the info

 

The early 1st gens had a vacuum operated ADD, all 2nd gens are fully electronic even though the FSM still calls it a vacuum actuator.
Being you have replaced both actuators your gona have to closely inspect the wiring and maybe get a meter out and start checking things manually.

 

Nothing to add, except that is a very sharp truck.

 

Sounds good man I appreciate it!

 

Thanks haha, it’s definitely coming together

 

If you’ve replaced both actuators with known working good ones I’d inspect the detent switch on the transfer case to ensure it’s operating properly, otherwise the ADD will not get a signal sent to it to engage.

 

This 4x4 is making me question myself as a mechanic lol. I have power all the way to the front actuator, my resistance at each wire is within the tolerance, front drive shaft will spin when I put it in 4 hi but not the front diff. I’ve checked all my electronics and they all work, all I can think left to do is solder the motor on the diff actuator and hope it works, other than that I’m just gonna take it to the stealership and see if they can figure it out

 

Have you considered swapping in a manual engagement transfer case out of an FJ cruiser? You can then choose to wire up the ADD independently on its own switch it just leave it permanently engaged. Completely eliminates the need for the 4wd ecu. You can even retain dash light functionality when engaging 4wd.

Though as I type this out it’s probably very expensive to get an fj case to Hawaii

 

I’ve been looking into it more and more now, I’m stationed in MS so the shipping isn’t a problem at all I’m starting to think once I get back from my deployment I’ll just go ahead and do it so I don’t have to fiddle with all this electronics nonsense

 

Are FJ Cruiser transfer cases that plentiful? Or are new ones available?

I thought that there weren’t that many FJs produced.

 

You can find them on eBay, some 4 runners also had manual shift T-case I believe. And for us we want a t case out of an automatic (so we don’t get full time 4x4) and those are gonna be a lot easier to find

 

I scooped mine on eBay for $300 shipped. You can find them sub $500 pretty easily.

 

When you select 4x4 , the transfer case sends a 12 volt signal to your front add to move the shift fork to the 4x4 position .
You would need a test light to verify 12 volts is being sent to the front diff actuator when you select 4x4 .
Because you already verified your components function leads me to believe you have a bad connection or a broken wire
Only when the front diff actuator moves to the 4x4 position will the light on the dash illuminate providing the wiring in the truck is good

 

I had the same thoughts and tested voltage and resistance at the actuator and it was all within spec, I’m starting to wonder about the 4x4 ecu

 

If you have 12 volts at the signal wire on the front diff actuator while the front driveshaft is spinning and your " ground wires are good " , the front diff actuator should move the shift fork to the 4x4 position .

You can try this with the front diff actuator removed but plugged in to visually see the fork move . Lots of members here at Tacoma World have tried this for diagnostic purposes

Maybe there is some info in the transfer case file to assist you
https://www.tacomaworld.com/threads/transfer-case-transfer-cases-in-first-and-2nd-gen-trucks.345652/