Weird transmission problem: no D, some R, L is going backward?????

Hey guys, yesterday my 2012 auto 4.0 (56k) taco transmission died on me and had to get a tow, and now Im trying to troubleshoot it and figure out whats wrong:

Little background:
Ive worked on dozens of trucks and cars, including full strip downs and ground up builds from scratch singlehandedly, so I do know my way around a wrench, but Ive never opened up an auto trans yet.

3 weeks ago I changed the ATF (followed the manual exactly on point as usual, absolutely positive I did it exactly right, and just re-checked the level again to verify I did it right). Ive driven several hundred miles since then too, so Im hesitant to point at the fluid change, but always possible.


Driving along yesterday on the highway, sudden lurch, a BANG, more lurching, then it was as if I was in neutral.


NOW: in D, it just baaarely is enough to move forward on a flat surface but mostly nothing, same for 2,3, and 4. Reverse does work but its lurchy. In 4wd, exact same results.
now heres the kicker, in L gear (not low reverse, but regular L) the truck goes BACKWARD?????? how is this even possible??!?!?

Any auto trans gurus out there have any ideas?
Again, fluid level is fine, I rechecked again.
Any ways to test for pressure going to the solenoids or purge the system etc?

 

needs a trans.. if its full of fluid and you got no D the trans is shot.. probably a failed trans fluid pump. with no fluid pressure available the clutch packs cannot engage gears. if you loose fluid pressure the clutches destroy themselves. needs a rebuild or new/used unit..

 

sounds like something let go in the valve body. you might need to drop the pan and check. when a big bang happens it is never a good out come. most likely needs to be rebuilt.

 

Isn't the powertrain warranty 5 yr 60k?

 

What trans fluid did you put in? Just curious.

 

Yeah exactly. Over 5 years of ownership?

 

Rebuilt title so doesn't apply
No CEL but being that it goes into reverse on low, good chance it would be a solenoid issue im guessing then or the pump. Any way to purge the system?

 

@gearcruncher maybe you have some input

 

used valvoline ATF, says right on it for use in toyotas.

I would be prone to believing it was the pump, but it works in Reverse (even though it does lurch), why wouldn't any others work? and L be reverse?

 

you should have never used that fluid in your trans. the factory fluid and the valveoline that is what caused your problem. toyota uses a special atf type ws for their sealed trans. when you mix that with say a dexxron 3 or 4 the molecules can't blend and it causes the metal and clutches to heat up due to improper lubrication and cooling. always use the same exact fluid that the factory filled it with. never ever mix two different types of atf

 

As already stated a bang is never good. Drop the pan and check for debris. Lots of junk, find a replacement.

 

Son of a b*tch. It literally even says toyota transmissions on the front too!!! But what I dont understand: Its been 3 weeks and hundreds of miles since, and It was only after driving 5 mins or so in winter, and the transmission didn't have any warnings or anything, just all of a sudden happened, theres been several other times driving 2+ hours and no slippage or gear drops or anything….?

 

Exactly which Valvoline did you use
They have multiple ones

 

That Valvoline ATF would probably work on my 4 cyl transmission (which is Toyota), but yours requires that special Toyota WS ATF.

 

it does say toyota but not for sealed transmissions. it probably was ok till it got cold and plugged a venturi inside the torque converter. or it could have plugged a valve and cause a solenoid to go bad. it's hard to say without looking inside of it.

 

Valvoline does make a WS Fluid so it dependeds on which one he bought

 

max life Dex/merc LV Gonna go ahead and assume that's not or sealed. Still find it hard to believe that that small of a difference would cause almost instant complete failure, in a short drive instead of a slow development of problems then dying X/

 

Actually that is WS compatible.

http://content.valvoline.com/pdf/maxlife_atf.pdf

Wish I could help you OP, maybe gearcruncher will be able to give you an idea.

 

Interesting ...