4x4 Won't engage with engine running.

My 2008's 4wd has been acting up recently. It is a 6spd manual transmission, and until a couple months ago I've never had an issue with the 4wd. Where I live and work I need 4wd regularly, so it's becoming an annoyance.

Here are the symptoms:

The 4wd will not engage if the engine is running. The lights don't even flash.

However, as soon as I turn the engine off, and turn the key back to on (mind you the engine is off) 4wd engages perfectly. Turn the engine over and it works fine. Until I shut the engine off again, turn it over and then again... nothing. Perhaps an overload on the electrical portion of the 4wd with the engine running?

I am pretty sure there is an electrical problem somewhere. Which I don't know that much about... if it were a mechanical issue I'd have no problem.


As you can imagine this is really annoying when I need 4wd on the fly. It sucks having to shut the truck off to get it to engage.

Also, tried talking with toyota about it. No one I talked to had heard of anything like this... Big help... So here I am turning to the incredibly large knowledge base of TacomaWorld!

Thanks in advance!

 

ADD actuator is likely the culprit. Easy replacement 4 bolts, one electrical connector. Takes about an hour by the time you drain the diff fluid and refill.

 

thanks for the input! I'll look into that. Where'd you order yours from? Just for future reference.
I'll make a short video to show what is happening when I get home from work.

 

The following thread has a couple of Tacomas with the same problem, with different solutions:

https://www.tacomaworld.com/threads/4x4-only-engages-when-truck-turned-off.270102

 

I think I ordered it at one of the online store, they were the cheapest. See here for when I replaced mine, it has the part numbers from Toyota

http://www.rocksolidtoys.com/forum/showpost.php?p=8102&postcount=18

 

thank you! this is exactly what is happening with mine. Think I'm taking off the front diff actuator to have my way with it... See if I can better diagnose the problem.

And thank you too psu! It's funny... I've been looking at the rst fj t-case swap for a long time before this was ever an issue. This might be the time to get rid of the stock electrical bull**** altogether...