Need a method of measuring Transmission Temp

And that's exactly why I have a transmission temp gauge.

 

Yes my original plan was actually to have a puller fan but it wouldn't fit that way. The fan I have in there is reversible so I still may have a buddy make me some different brackets that bring the cooler closer to the grill. Unfortunately my fabrication skills are limited so this is how it's going to be for now.

That's the plan. I'm going to plumb it today. I want to leave the oem stuff on there as long as the truck is under warranty. If I blow it up on a road trip it'll be easy to return it to stock and pull the bigger cooler while waiting for a tow truck to take it to a dealer for warranty

 

You did your homework . Why does Toyota turn on the dummy light so late . At least give us some time to pull over and cool the trans down a little ,Lets say 235 degrees ? Nope..... 302 degrees and completely cook your fluid

 

https://www.tacomaworld.com/threads/trans-temp-sensor.456998/#post-13594000

 

More of an "it's ruined light "....
I've read that the two temp readings in the trans have specific functions. The hotter of the 2 is at the torque converter and will prevent the truck from using overdrive gears if it gets too hot and the lower of the 2 is at the pan and will put the truck in cripple mode if its too hot? Any truth to this?

 

I do worry about the extreme event... I'll admit that I abuse my truck a bit. We have a jayco 195rb baja about 3700lbs loaded. I've pulled it through sand and mud in 4lo a time or two and didn't have the scangauge during those events

 

I will have to get back to you on this answer .
What I do know ... The transmission will not go into overdrive or converter clutch lock up until operating temp is achieved .
There hasn't been enough overheat complaints on this forum . I haven't done any research regarding what temps will activate limp mode or prevent overdrive gears . Thats a good question mind you . I will jump into the factory service manual and have a look

 

I was thinking it would be nice to find a solenoid that was temp activated or manually activated to where you could bypass the extra cooler after the stock cooler and only use the secondary cooler when it is really needed. I bypassed the radiator on my last two 4wd SUVs and was running the stock cooler with 135 -205 range. I never got above 215. Have two coolers mean those cold mornings takes forever to get the transmission temp up.

 

The torque converter on the 2nd gens won't lockup until the engine coolant hits 140°. Has anybody watched the second gen on the Ike gauntlet (TFL)? If you watch the whole thing you'll notice that it will go from screaming at redline for a while to lugging the engine with seemingly no change in road grade, I wonder if it isn't upshifting to lockup the converter to cool they transmission fluid? No idea what's actually happening there, but I'd love to throw a scangauge on it and watch the tranny temps as they're making that run.

 

This is why I recommend the True Cool Low pressure Drop transmission cooler as an aftermarket alternative because they only activate when the transmission gets hot . Not a solenoid inside , but a mechanical heat spring

 

My truck has seen its fair share of abuse in its day. I used to tow heavy loads quite a bit and never worried about trans temps. Fun fact: on a 3-2 downshift with that much weight it will chirp the tires. I'm fairly certain that towing those loads of hay out of a steep gravel driveway in 4x4 has actually stretched my transfer case chain a little over the years.... it's 10 years old now and has 80k... never had a major repair and never stranded me. Only thing I've really done aside from routine maintenance is the ECGS bushing on the drivers side... which it didn't need yet, but I knew it eventually would, so I went ahead and did it.
Disclaimer: *for those of you that are inevitable gonna say "oh that's dangerous...blah blah blah" I only tow this on a backroad at low speeds from farm to farm. It's not like I'm tearing down the interstate with it, and I'd venture to say that I've towed as much (frequently) or more than just about anybody here. Also, I do not recommend, and am not advocating overloading your vehicle or towing/hauling beyond your vehicles specified capabilities: doing so will shorten the life of your vehicle and potentially endanger you or others around you.

 

$59 Tru-Cool Long brand Transmission Cooler External Thermal Bypass 708-4739P6

https://www.amazon.com/Tru-Cool-Long-Transmission-External-708-4739P6/dp/B008BTJFJ4
This bypass valve sounds similar to what you are describing. I didn't use it because I thought it would be difficult to properly refill the trans. I'm probably overthinking it but you would need to get you trans temp up to 180f for that valve to open and fill the new cooler. Since your check temp is between 95 to 113f so you'd have to warm it up to at least 180 then let it sit for a day again until it's cool enough to check. You could probably put a heat gun on the valve and get it to open but I found it much easier and cheaper to buy a cooler with a viscosity bypass. Both tru cool and hayden coolers have some kind of viscosity bypass.

 

Those let about 10% of the fluid pass even when closed, if you let it idle up to temp while checking the level, I'd imagine that there wouldn't be any air left in the lines or coolers by the time it got up to temp.

 

@gearcruncher , do you, or anyone, know at what temp the thermostat on a 2018 Tacoma trans fluid cooler will open? I’ve been driving a lot of highway miles lately and have not seen a pan temp yet over 185*F. I don’t think the cooler is even in the loop yet. I wanted to know before I start pulling my travel trailer in the hot weather. 3200#, loaded.

 

I’m not sure but I think it is like 205 degrees which I think is too high. Toyota wants those trannys to live at 175 degrees. I pinned my thermostat on the tranny while towing heavy trailers.

 

2nd gen with towing package was 190
Not sure about 3rd gen .
205 is pushing it .
My suggestion would be to dump the factory cooler and place a larger cooler in place .
A good investment for around 100 bucks

 

Use the app OBD fusion then a ten buck OND plug and get temp and everything else you want

 

I keep my eyes peeled with this in deep snow.

 

Thanks. I want to keep an eye on what temp it gets up to and how much it will cool down when the cooler kicks in. If it’s not enough after a few runs with the trailer I’ll look into replacing the cooler.

 

Damn! I was thinking about just keeping my stock unit until I saw this. I'm assuming that you can display boost as well?