4x4 light keeps blinking

How strange, like I said I replaced both, and took off the negative battery cablewhioe I did everything also flushed fluid and all in the process, I know there are some fuses behind the glove box you could check as well

 

Transfer case has enough fluid?

 

Where behind the glove box?
I thought there were only 2, under the hood & below the steering wheel to the left

 

Yes, just replaced couple hundred miles ago

 

There was a thread a few days ago where several folks were experiencing exactly what you describe. In one case, replacing the limit switches on the tcase corrected the issue; I believe another guy replaced the ADD actuator and reset the ECU and found success as well. It's a frustrating situation and it seems like it's a combination of the actuators and sensors causing this with no easy process of elimination to find the culprit. If you've replaced both the 4hi and 4 lo limit switches on the tcase in addition to the ADD actuator, verify both actuators are properly synced to the dash switch position and try resetting the ECU just to see... Have you opened up the tcase actuator just to confirm there's no corrosion possibly preventing the position signal from getting to the 4wd computer?

 

How would I reset the ecu?
I’ve checked the t case actuator & it looked just fine

 

Just disconnect the negative lead off your battery for 5 minutes or so. I'm not wagering much on that to fix it, but it's worth a try if you haven't already. Other than that, I'm hoping someone else has some suggestions for this - it seems like it's becoming more prevalent as these trucks start getting up in mileage.

 

I’ll try that

The actuator looks fine, it shifts to 4wd seemingly but won’t go back to 2WD unless I take the key out & insert it back in

 

I don't know the accuracy of this statement and have not seen an assembly diagram to confirm this, but I do recollect someone saying that a dealership or shop had claimed that there are internal position sensors inside the tcase for the shift rod that can wear down. Once they fail, the position signal that is sent to the 4wd computer may not be triggered, which will absolutely prevent the ECU from shifting in/out of 4wd as it requires a few true/false statements from both the ADD / Tcase actuator to make a shift.

I have no idea if those internal position sensors really do exist, and this is nothing but rampant speculation, but if they did, it may be possible the sensor for the 2wd position is functioning properly allowing you to get into 4hi, but once in 4hi, the computer does not receive confirmation you are in 4hi, hence the flashing 4wd indication / inability to get in 4lo/2hi. Upon turning off/on your truck with the switch in 2hi, the computer doesn't know you are in 4hi and simply shifts back to 2hi. Makes some kinda sense in my head, but I need to find an assembly diagram to see if those position sensors are a thing.

 

Gonna take it into a shop and see what going on man, it’s very frustrating dealing w this crap

 

Hopefully you can find one that's familiar with the system as a whole - My friend had dealt with this for awhile and it seemed like every recommendation from a shop involved the entire replacements of components rather than any systematic troubleshooting to get to the specific issue. Wound up being corrosion of the ADD actuator and a simple cleaning of terminals and soldering fixed it right up, but there's clearly more at play in your case.

 

been a while but did you ever find out what was wrong??

 

Have a look here.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

It was the both the front diff actuator, and the transfer case actuator that were out, and that's what caused it

 

ok.
mine was blinking too at one point but i didnt know i had to put it in nuetral first. it seems to work fine if i put it in nuetral first

 

I have a 21 Tacoma TRD off road and took it to the dealer for this issue. Not covered under warranty. $3200 to replace the 4wd actuator in the transfer case. SMH...

 

Did you get it done? It shouldn't cost that much

 

Yeah just got the truck back today. Mostly labor.

 

I'd ask to see the old actuator.
I bet they swapped the electrical actuator, but not the shift rod.
And I bet you got billed for the "whole" thing. Rod and all.

If they didn't replace the rod, it's a 2 hours job for a Tech that's done it before.

 

Agreed just replacing the actuators, which was the case on mine, my dads 3rd gen, and a friends 3rd gen cost me no more than 400$ in parts, and the work time was maybe 2 hours