Transmission Shifting Issues When Cold

I have a 2015 Tundra with about 55,000 miles. I just had the transmission fluid drained, not flushed, new OEM filter, gasket, and Toyota ATF WS fluid installed by a reputable mechanic. It was a total of about 6 quarts drained and replaced. Proper procedures were followed with the transmission oil cooler thermostat.

After about one week I am now having issues with the transmission shifting in gear forward or reverse until the fluid warms up. The tach bounces between 1000 and 2000 and sometimes the truck won’t move. After the fluid warms up, no issues at all.

I had the mechanic double check the fluid the other day following Toyota’s specifications. Fluid level is fine and no leaks.

When they took the pan off, no metal shavings on the magnets and the fluid was just slightly dark red.

I changed the fluid because about three times a year I haul a travel trailer.

Any idea’s why this is now occurring? Never had any issues before the fluid change.

 

How sure are you the mechanic is checking the fluid correctly?

 

I had a similar issue on my 2012 with about 160k miles. I took it in to the dealership for a drain and fill, fixed it right up

 

Drop the pan, reattach all solenoid connectors.

 

Define what you mean by warms up. What is the outside temperature when this is occurring? I have read somewhere that these transmissions make adjustments to their pressures based on the age of the fluid. Supposedly there is a place in Techstream to notify the computer of fluid replacement. That is part of the reason I don't replace more than a few quarts each time. Hopefully someone else who knows more can confirm one way or the other. Good luck!

 

The second time so took it to him, he showed me the Toyota procedures which are spot on with what I have read in Toyota forums and on Toyota service bulletin.

So seems like the best course it to take it now to a dealership, have them drop pan, check solenoids, and refill? Sound right?

And yes, he used TexhStream to notify the ECU of fluid change.

 

At 52k old fluid was still good.

Also it makes no sense to reset fluid overheating counter. If it counted enough times, the transmission would apply torque convertor lockup wherever possible to reduce heat generation. The driver will certainly notice it. But it takes some serious beating to get to that threshold.

 

I personally know a few folks who disturbed solenoid connectors while doing pan job or simply not clicking them all the way in while replacing the valve body. All you described indicate that it is very likely what happened to your transmission.

Tell your mech about that, he can quickly drop the pan and fix it. Can even reuse good fluid to cut cost.

 

Inquire about what I said above. Does the computer have a method of controlling the pressures based on fluid age? Seems logical, but I truly don't know enough and I don't think it's published enough to be common knowledge here either.

 

No. It tweaks linear solenoids pulse-width modulation to achieve better shifts, but it has no way to sense fluid properties.

 

I wasn't referring to overheating counter. As I understand it, the computer simply compensates by adjusting pressures based on the fluid age regardless of the temperatures it reached.

 

No. All it looks at is how good the shifts are done. Which, yes, relates to fluid age (friction modifiers are consumed over time), but also mechanical wear, temperatures, etc.

 

One more thing came to mind: what kind of filter was installed? When I was doing my transmission (AisinWarner, but not in Toyota) I got a generic filter in overhaul kit and I didn't like its sealing leap. Original AW filter had it glued, while aftermarket filter - not. I imaging it can be sucked it partially, resulting in fluid being aired up. The mech can recheck or replace the filter when inspecting your transmission.

 

So up here in Ohio night temps are in mid 60s, so I assume the fluid when cold is somewhere around there. After driving for about 20 minutes, the issue seems to go away.

Another weird thing, last week we were pulling our travel trailer home from a camp site around 1 hour away in tow/haul mode. No transmission issues. Then next day, early morning I had issues when putting it in drive or reverse. Put it back in drive, drive slow for a minute in the parking lot and it started shifting fine.

 

Just said I read it somewhere and OP should research it more in depth. Never claimed to be an expert. I know the fluid breaks down and it makes perfect sense for the pressures to adjust accordingly. Not trying to argue all day, just sharing what I read.

 

OEM filter and o ring was purchased from local Toyota dealer.

 

I think maybe you have a solenoid going out and it works better once it gets heat applied because the temperature change affects the size of the components inside the solenoid.

 

If you did the fluid change after your trip, the problem was already starting and had nothing to do with the fluid change. Just coincidence.

 

If it was a solenoid, would it throw a code to the ECU? I’m not seeing any codes with my code reader nor did the mechanic with his equipment.

 

Fluid change was done before our first camping trip. No issues with the tranny on that trip. It was a week later on our second trip the issue started. Both were about same distance, only difference is on the second trip I used an interstate route for about 40 miles keeping the truck between 60 and 65 mph. Was running between 2000 and 3000 RPMs on the interstate.

 

Maybe and maybe not, I don't know enough about it to answer that. I suppose it might depend on if it was totally failing or completely failed. If just sticky, maybe not. I simply don't know enough to say for certain. Just makes sense to me that it could be the problem because of the way temperatures affect the physical size and function of everything.

 

Maybe the detergents in the new fluid caused a little flake of something to become dislodged from within and it is now stuck where you don't want it. Perhaps it'll correct itself if you just wait and drive it after it warms up. I would be asking a knowledgeable transmission guy what he thinks about it all. Often times they have seen it all numerous times and can quickly diagnose the exact cause. My go-to folks are American Transmissions on Walker Ave. In OKC. can't hurt to call them up and ask a few questions, been around for decades and they know transmission work.

 

I have a 2017 Limited Tundra 60k with similar transmission issues (hard cold shift, over revving in low gears) and I've developed a theory after multiple trips to Toyota dealerships, techs and other mechanics that have not been able to solve the issue. I also do some periodic hauling about 6 times a year with my boat (5k lbs), trailers, etc. ***Disclaimer, I am not a mechanic, just a DIY tinkerer.

I'm sure this advice is out there, but despite my searches on several forums, I haven't come across it.

My theory is that when the tranny fluid is drained and refilled to the level that overflows at the check bolt, which is the toyota spec and tech training, it is initially a bit low. Then, when you tow and engage tow mode with the tow/haul button, that opens a valve where additional fluid is cycled through the transmission cooling system (pre2020 only) to help it cool from the shifting under weight of tow. The extra ATF fluid then sits in those lines. This process drains ATF fluid further from the main case, creating a lower level of ATF than what is needed in the main case, and exacerbates the rough, slow, etc shifting.

I too drained my transmission fluid thinking it was a fluid issue, and discovered that when the fluid is very low, the transmission will not even engage from Park to Drive. As I refilled to different low but not full levels, I noticed distinct shifting issues. The literature I found regarding the correct levels, consistently state that as soon as fluid starts to drip out of the overflow check bolt, the fluid is full. However, I think this is the minimum low level.

When I refilled the ATF fluid to a level that was a slow flow from the check fluid level bolt, my cold shifting, high revving, etc issues were resolved. This may be a level higher that what Toyota recommends, but my truck seems to like it and is shifting smooth after cold and warm starts.

Here's a very simple how to video to refill transmission fluid, with parts listed. Hopefully its a simple fix for you - just add a bit more fluid!

 

Do know if this helps but look up John Lombardo (Import Performance Transmissions) There are some know issues with our tranny's. Not that they happen much but this guy knows them. Here are some of the codes commonly thrown. All codes start with P. 2714 2757 0748 0741 0776