2015 sr5 transmission issues?

hey all I've been around awhile and this is my second Tacoma so i know these trucks pretty well but I've never had issues with a transmission before... little background i sold my 2013 Tacoma that was pretty well modded out because i bent the frame on it and fixed it and the truck never felt the same.. I then bought a 22 ford ranger that lasted a year and some change and the trans started to fail so I traded it in on this 2015 sr5 access cab 2 owner truck.

the issues:
over the past couple months I've noticed the transmission acting oddly that I never saw on my 13. it wouldn't be all the time or even constant at first... so for example I'm on the highway cruising about 65-70mph and I need to get around someone so you go to accelerate well the truck would feel like it shifted and load down like its pulling a trailer but it wouldn't go faster? it would just sit there in a higher rpm and not do anything.. at this time you could either..

A. let the truck coast for a few mins and then let it sort it self out or
B. slap the shifter to 4th and see if it would down shift which it would. (only did this once at highway speeds when it wouldn't shift)

after awhile the issue would become more common even in town roadways at speeds below 50mph..

most recent incident was I saw a newer jeep gladiator hit a bump and basically the tailgate was about to fall off so I went to accelerate from a corner. to catch up and let them know so the gate wouldn't fall off on a road way.

(the image below shows where I started accelerating at and where the truck felt like mush red mark is the jeep which use to be 2 car lengths in front of me)
looking at the little markers you can see (sorta lol) how the truck acted.. the jeep was about 2-3 car lengths ahead of me and I went to catch up around that corner but as I did the truck went into idk a limp mode? and refused to shift and felt like mush... me and the gf both felt the truck down shift but then it just sat there as if its towing a heavy trailer up a steep hill and struggled until I let off the gas and let it coast a bit and then it slammed into gear... after that I was able to catch up to the jeep and warn them of the gate. the black line shows how long I had to coast before the trans did well transmission things..

issue from yesterday:
I was at a red light and waiting to go and when the light turned green I just rolled onto the gas to let the truck go move. no I wasn't stomping on the pedal I was just letting the truck cruiser forward while on the phone with the gf. I had barley made it into the intersection and noticed the truck had gotten a lot louder and really wasn't moving that fast. I looked down at the dash and it was barley doing 15ish and at 4500rpm.. I let off the gas to see if it would shift and it wouldn't I then tried putting it in a different gear since it wasn't shifting and it ignored that as well.. the truck took a good bit to actually shift and it took me using the manual option to get it to shift. after that the ride home the truck felt like a slush box tbh..

today issue:
drove the truck in today since wasn't feeling up to riding my cruiser into work. and overall the truck was fine minus one spot on a hill on the highway where I need to accelerate because cruise control wanted to do a down shift. I was doing 70mph and felt the truck shift and hit a load and noticed I was slowing down... when I took the truck out of cruise control and reached the top of the hill the truck then shifted and I went to work fine with no more issues.

things in common:
all my issues have happened on hills... once the truck gets on a hill it seems to not work properly..

plans ATM:
ATM I'm thinking of changing the trans fluid as a drain and fill not a full flush but this doesn't seem to be a fluid problem... my last Tacoma had 140k hard abused miles and I honestly never touched that trans on that truck and it was flawless and worked every day and towed without an issue.

id love to hear what others have to say and or ideas on what the issue is. ATM I'm worried I got into another truck with a transmission issue and will have to get rid of it or look into replacing the transmission which is a lot of money to do.

id also like to point out I did go to Toyota but since they couldn't replicate the issue (man this is familiar to my ford!) they couldn't tell me anything since it has nothing on the dash as well..

since people will ask about info on the truck here ya go.

2015 sr5 access cab long bed 4x4 truck
truck is leveled with Bilstein 6112 and 5160s in the rear with Bilstein upper control arms
tires/wheels: 1st gen tundra wheels with cooper st maxx 275/70/17 tires.
us off-road front bumper with warn synthetic 10k winch.
leer campers shell.
4.0v6 5 speed auto.
miles 102k

overall a very simple truck tbh not a lot done to it and don't have loads planned to do with this one since its job mainly is to pull trailers with bikes and other odds and ends.

 

First thing I would do is check the transmission fluid level and condition.

 

thats kinda the plan is to check the fluids and drain and fill.

 

Dang, sorry to hear about the troubles.

Since the drain and fill was mentioned I’ll throw it these out there as the first two are easy, but clean the MAS and maybe throttle body. Might help, might not. Only takes 5-10 min.

while unlikely, could also be clogging in a catalytic converter.

Im no expert…

 

ya man its a bummer.. i like this little truck a lot but man what the hell is with my luck! i babied the ranger and to be fair it was a failure from the factory.. but a toyota??? i didnt expect that on my bingo card to have problems with a truck i trusted even if i got it with higher miles...

ill take a look into that as well.

im not sure on that one tbh? i mean anything is possible but that would be an odd one!

 

hope that the flush and filter fixes it. Might be time for it anyway with higher miles.

I suggested since it’s not consistant and seems like something is going on to make it shift or not. Doing that fix a random surging issue I had with mine, but 2015 and 2020 are different beasts.

My buddy had a similar sounding issue on his Ford, like it would bog down while driving. I’ll have to ask him what was done to fix that.

 

maybe unsure my grey 13 i never touched its fluids and it was fine this truck (after looking at records) it was done at 60k miles so its fluid should be fine? still plan to do it and see if anything changes..

oh i know you are good man lol

ya i had a similar issue with my ford ranger lol thats why i got rid of that truck was transmission issues and get this tacoma.

 

I would follow DM93 advice, I have a 2015 and it showed some of the same symptoms. I checked the fluid level and It was 3/4 qt. low. This problem has been attributed to being low from the factory based on if you have a transmission cooler. The transmission cooler holds an extra qt.+/- . Once I adjusted the proper level, my problem did not exist. I was 3/4 qt. Low.

 

the oil was changed at 60k miles from one of the past owners. so it could be low but i do kinda doubt it.

 

Mistakes get made especially on transmissions such as this where there is a very specific fluid level check procedure, many people just measure what they drained out, put that amount back in, and send it.

In any case doesn't hurt to check, first thing I do for a transmission complaint in addition to checking for trouble codes.

 

i agree things can happen and people do just send it haha i still plan to do it this weekend it just doesnt seem likely but who knows.

sadly no codes on the dash either i would expect it to but havent seen any yet!

 

You don’t really know if the previous owner checked it correctly. Even local repair shops that check things don’t always do the check correctly. In the future if you want to see if they checked it right. When you go to pay your bill, just ask them at what temp. did you check it at when you pulled the overflow plug. If they look at you with a blank stare. Then you know.

 

Most likely the shop drained the pan, measured or estimated what came out and then put the same back in

 

that is correct on if they checked it correctly i honestly dont know if they did. all i know is it was an older couple that owned it first and then another older couple that had it before me and then i got it.

 

that is possible yes

 

You said older people had it before you so some of it could be learned behavior, modern automatics tend to do alot of learning. If you drive them like an old lady it will tend to get quite lazy with downshifts but if you drive them like you stole it they will tend to downshift more readily.

Once you verify the fluid level you may want to try a battery disconnect to clear any learned values.

 

correct older people did own it before me but ive owned the truck for almost a year now and have replaced the battery already so any learned in driving behavior is long gone.

atm after talking to a few shops they are thinking its a torque converter failure. still need to pull fluid to tell but atm that is what shops are thinking until they can actually get hands on the truck and look at it.

 

Ah ok, it was just a thought.
I do know that often times you can tell how someone drives a vehicle by how it behaves when another person with a different driving style gets in it.

 

ya ive had that with my moms newer kia lol its pretty odd on how it does that.

for this thou id have to say thats not possible since of when and how its happening

 

i took the truck to a well known transmisson shop today that my family trust well.

he drove the truck and was unable to get anything to show up on his scanner but did feel what i was talking about with the transmisson. he told me he will be gone until tuesday but after that i can bring it by and we can drop the pan to take a look inside the trans since he just had to replace a trans on a tacoma with the same symptoms now the only difference was this truck had close to 200k miles on it.

atm he gave me three options since he cant say for sure what it is until he pulls the pan on the truck.

A. drive it until something happens but that could leave you stranded hours from home. i have a trip coming up not this weekend but next so that could very well happen or not atm nobody knows.
B. find a low mile transmisson preferable 60k miles and under to swap into since he does belive atm something mechanical is wrong and is expecting metal bits in the pan.
C. sell the truck and get something else and let it be someone elses problem

so that is where im at atm..