Caught between cat thefts and a hard place

Been enjoying my freedom not worrying about my cats being stolen but I’m having the truck checked out next week. Was towing in Massachusetts Connecticut and southern Vermont trailering approximately a 6500 pound landscaping trailer and tractor. Didn’t go over 65 kept it about 55 to 60 on average and used tow haul on the inclines. After about two hours of that I got the overheat transmission warning light pop up. fortunately was right when I arrived at my cabin in Vermont. It was sunny and about an 84 to 86° Midday excursion. I may have to get the much hotly debated and ad nauseam discussed transmission cooler. I’ll be curious to see what the dealership says on my appointment next Tuesday.

 

When you say revive, it’s a 21 with 11,500 miles on it. Not exactly sure what you’re referring to?

 

Doesn't matter how new it is. ATF boils at 300+

 

Were you driving in S4 or D?

 

Dealer is going to say they can't replicate the issue and that the transmission is functioning as intended. Been there, done that, they DGAF if the trans cooks because Toyota say the trans cooler isn't needed.

 

That ATF boiling point chart can't be right.. Are we talking about 300 to 400 degrees C or F? 300 degrees C seems a bit much which equals 572 F!

 

My guess in drive like the manual states but only tow/haul on inclines. I've tried towing in drive using T/H watching the scan gauge and it's a recipe for a transmission pan turned dumpster fire. And that's with a < 3 ton TT.

It's S4 T/H with select use of 5th for this kid. The transmission spends way too much time with the TC unlocked when in drive or even S5. Even when in T/H.

I remember another poster hitting the limits and the dealer recommended a fluid change.

 

I drove a combination of both. Though driving in tow/haul mode should compensate for that from my understanding.

 

If you look through this thread, there is talk of a TSB about the trans overheat light. The dealer might do this if you take it in. This pic was from post 517. TSB talk starts around page 18.

https://www.tundras.com/threads/transmission-cooler-missing…i-know-i-know.95783/page-18#post-2450048

 

Tow/haul in S4 is what you’re supposed to use for towing per the owners manual. S4 is your last non-overdrive gear, and the only non-overdrive gear that you can lock the torque converter in. If you tow in D, your transmission is constantly shifting between gears 4, 5, and 6 and isn’t staying locked up in any of them. That is what generates heat.

I absolutely hate that the 19-21 trucks don’t come with an actual air cooler in addition to the oil puck. That’s why I put one on at 3k miles. There are a couple good YouTube videos on how to do it and how to check your fluid level after adding so you don’t overfill. Easy to find if you search. @Genuine Cooling Systems is where I bought my cooler.

 

In my owners manual it's rather vague on where you should place the transmission for towing. It leans toward towing in drive but selecting S4 going down grades for engine braking. Tow/Haul mode is a definite yes though. If there's one change I'd like to have it's that the T/H mode default to on when a trailer is connected to the 7 pin.

 

Transmission fluid does not boil at 300F. The C is probably correct. Not sure this directly relates to anything related to transmission wear etc, but good to get it checked out.

 

I scoured my manual and couldn’t find anything related to towing in D…do you have a page number where it says this?

 

Look at the bullet point in the middle of page 210. Vague to say the least. I called Toyota to get their interpretation and asked my dealer to read it and both said tow in drive but use S4 to descend hills. Being someone with a technical writing background the statement leads to believe both clarifications although I believe it isn't written correctly.

 

Yep, right there. This is a list of towing tips, and I don’t read that to say that you should shift into S4 only for going downhill. Nowhere does it say to tow in D. S4 prevents you from using the overdrive gears which don’t stay in lockup very well except when cruising on level ground. On page 212, the manual gives a checklist of what to do before towing, and that’s where it says to put it in tow/haul mode.

To me, it’s saying to tow in S4, in tow/haul mode, at ≤65mph.

 

It could be alot clearer.

 

It was bad enough we didn't get the transmission cooler so they changed the shift parameters to heat the fluid even more. The melted icing on the burnt cake is the unclear instructions regarding towing in the owners manual. Oh, almost forgot: No trans temp gauge. Just a light to tell you that your transmission is now effectively half lifed.

 

With a Tranny cooler = T/H + D

 

I put a cooler on my 19, piece of mind, no S mode needed unless it's extreme !

 

Got the kit from Nick(site member) local trans shop installed for @300 bucks. So say $1,100.00

 

I hear you. What I posted is from my manual (for the 21MY); maybe older manuals are slightly different in their towing tips? I read it as stay in S4 and here is one reason why…the other is left unsaid…is it not also conventional wisdom to not tow heavy loads in overdrive gears, especially on non-HD trucks, and extra especially (lol) on non-HD trucks that deleted their external cooler?

I put a cooler on my truck as well. Bought the older Hayden kit from @Genuine Cooling Systems and pieced together the OEM parts from McGeorge Toyota and Lewis Toyota. I was into parts and fluid for $700. Did the install myself. Fairly easy.

 

What does the TC do, and what does it mean "locked in"?

FYI, I installed Nick's kit and towing my 4400GVWR TT, the scan gauge won't go over 195F for the pan temp.