Towing Trans and Temps

[bpfick]

Those who tow in summer type temps vis-a-vis shoulder season or even much cooler and have an automatic transmission temperature gauge/sensor, a question.

How much difference does the ambient, outside aire temperature effect what you see in trans temps while towing? What effect, if any, does towing in say 40F weather versus towing in summer's heat in the 90's have? What factual, actual readings do you re-call and what are your remembrances of the contrast?

Very much appreciate your experience in this. Thanks.

[Darwin Maring]

The transmission radiator is normally up front of the vehicle radiator so the higher the outside temp, the less cooling of the trans oil.

[steve dunham]

It depends on your automatic transmission and whether you are using conventional transmission fluid or synthetic fluid.
Try to find a forum on the Web for your particular vehicle and you will probably find your answer .My 2014 Ram truck's transmission temps seemed high to me compared to my old 2011 truck (8 speed versus 5 speed) but I soon discovered they were normal for my 8 speed transmission.

[Carl V]

The transmission wasn't really running hotter in warmer climate but it took a little more time to cool down after a climb or some stop'n go in traffic.
Actually the driving conditions (hilly vs flat, constant speed vs city driving) have a much greater impact on transmission temps than the ambiant air temperature.
I found that city driving is the worst: high power bursts with unlocked torque converter, numerous gear changes, low airflow on the transmission cooler.

[bpfick]

Originally Posted by Carl V

The transmission wasn't really running hotter in warmer climate but it took a little more time to cool down after a climb or some stop'n go in traffic.
Actually the driving conditions (hilly vs flat, constant speed vs city driving) have a much greater impact on transmission temps than the ambiant air temperature.
I found that city driving is the worst: high power bursts with unlocked torque converter, numerous gear changes, low airflow on the transmission cooler.

Thank you. This is the kind of feedback that is very helpful. Am I to assume you have a gauge you could watch that monitors your transmission temperature?

[bpfick]

Originally Posted by steve dunham

It depends on your automatic transmission and whether you are using conventional transmission fluid or synthetic fluid.
Try to find a forum on the Web for your particular vehicle and you will probably find your answer .My 2014 Ram truck's transmission temps seemed high to me compared to my old 2011 truck (8 speed versus 5 speed) but I soon discovered they were normal for my 8 speed transmission.

Thanks Steve. Your truck came with a transmission temperature gauge I take it.
My truck is factory filled by Toyota with synthetic. My Ford Escape was as well.

Neither have/had a transmission temp gauge, thus my questions about ambient air temps of cold season towing vis-a-vis the hot of summer and what differences you may have seen on your gauge. Thanks.

[gordon2]

Originally Posted by bpfick

..
Neither have/had a transmission temp gauge, ...

You might want to look into https://torque-bhp.com/
I use it for my Toyota to get a tranny temp reading.
Toyota is secretive with their ECM data but some clever people published the info needed to add a tranny temp gauge on the Torque app. I can't be sure the temp reading is accurate but I think its pretty close and it does track what I would expect under different conditions. You might get lucky and get a ready made tranny temp gauge in the app. You need to get a bluetooth OBD2 reader. The cost varies a lot but the one I got cheap on ebay works OK.

The highest tranny temp I saw was on the way back from the beach, a few hours into the trip on a hot summer day, when the traffic became stop and go, just creeping along, for 30 minutes.

[steve dunham]

Originally Posted by bpfick

Thanks Steve. Your truck came with a transmission temperature gauge I take it.
My truck is factory filled by Toyota with synthetic. My Ford Escape was as well.

Neither have/had a transmission temp gauge, thus my questions about ambient air temps of cold season towing vis-a-vis the hot of summer and what differences you may have seen on your gauge. Thanks.

My Ram truck shows transmission , oil and coolant temperatures on the vehicle EVIC . I seldom check the EVIC but I do notice that
the transmission shifts differently when it's 30 below versus 80 above. My truck has the larger radiator , an engine oil cooler and a transmission cooler.

[Carl V]

Originally Posted by bpfick

Am I to assume you have a gauge you could watch that monitors your transmission temperature?

I installed one on my previous tow vehicle (Nissan Quest minivan), a mechanical unit with the probe mounted in the output line from the transmission (before the rad and aux cooler). Worked nicely.

Now my current TV ('06 Toyota Highlander) didn't have one, and I planned to add one eventually, but last year someone finally figured the computer code required to extract this data from the Highlander's ECM. As Gordon mentioned, Toyota doesn't publish this kind of info and it wasn't 'discovered' until last year to my knowledge. I've been using a Scangauge for years, now my Scangauge can display the transmission temp.
I actually coded my Scangauge only last fall, and I haven't really towed anything but my utility trailer since, so it's hard to tell how good it works, but so far the displayed numbers make sense.

[Jon Vermilye]

I added a Scan Gauge II to my 2010 RAV4 in 2012 to keep track of the transmission temperature. Once the engine warmed up to operating temperature, the transmission temperature definitely ran hotter when temperatures were over 85°F or so. I found the code for the Tacoma (at least TF1) also works for the RAV4 V6.

From the RAV4 Owner's Forum:
"Transmission temperature for 2010+ tacos. Enjoy!

Transmission Temperature 1 (Degrees F) 2010+
TXD: 07E02182
RXF: 046105820000
RXD: 2808
MTH: 00090005FFD8
NAM: TF1

Transmission Temperature 2 (Degrees F) 2010+
TXD: 07E02182
RXF: 046105820000
RXD: 3808
MTH: 00090005FFD8
NAM: TF2
*
It’s theorized that TF1 is the pan temperature, while TF2 is the converter outlet temperature so TF2 will fluctuate much faster than TF1 will."

[ruscal]

Fredrick,
As you would expect the ambient temperature surely affects transmission operating temps. Other things also will affect temps, such as load carried, uphill grades, what gear the trans is in, and to a minor degree the type of fluid used.
I have an old Chevy 1/2 ton v8 automatic. I opted for running a very large air to fluid cooler in a different air path than piggy backed with the radiator, or internal to the radiator. I installed a temp gauge into the transmission pan. In testing I discovered the trans would run cool in any temperature environment as long as I maintained enough speed to keep the air flowing through the cooler. I took it up into the mountains during a traffic jamb where the system failed miserably. We could only travel 10 MPH for 25 miles uphill. My temps were hovering at 240F. The transmission was not slipping, nor under any hard duty, yet built heat just from not being able to lose the fluid heat. I then descended the mountain using a different highway where I could travel 40+ MPH and the temps went down to under 200F in just a few minutes. I would have to add an electric fan to fix the problem, but decided to install a manual trans in stead. It is interesting to have a good gauge and watch what happens under different situations.
Russ

[ATHiker]

Like Jon, I use a Scan Gauge II to monitor the transmission temp on my Toyota Tundra. On up hill stretches, the transmission temp can climb very quickly to 230+ deg. I can manually downshift the auto tranny and the temp will drop. The Tundra also uses synthetic fluid, but the danger with high temps is to the transmission components that cannot withstand prolonged exposure. I have considered replacing the transmission cooler with a larger one or one with a cooling fan.

[AandB]

Also using the ScangaugeII in our 2008 Toyota Sienna towing a Casita 17. Had installed an additional tranny cooler. Temps in winter are in the 130, 150 or so in summer when not towing. When towing temps are steady at 178 unless on a incline or idling in traffic where it will climb to 200. As soon as the cooler get some air flow it returns to 178 or somewhere near. Highest tempeture I've seen is 215. Using sythetic oil and no excessive speeds...55 - 60 mph. With the ScangaugeII also able to monitor rad fluid temps. If I had to do it over again I would set it up so the additional cooler would be by-passed in winter.

[bpfick]

Originally Posted by AandB

Also using the ScangaugeII in our 2008 Toyota Sienna towing a Casita 17. Had installed an additional tranny cooler. Temps in winter are in the 130, 150 or so in summer when not towing. When towing temps are steady at 178 unless on a incline or idling in traffic where it will climb to 200. As soon as the cooler get some air flow it returns to 178 or somewhere near. Highest tempeture I've seen is 215. Using sythetic oil and no excessive speeds...55 - 60 mph. With the ScangaugeII also able to monitor rad fluid temps. If I had to do it over again I would set it up so the additional cooler would be by-passed in winter.

Andy, if I read your reports correctly,

Winter, not towing 130
Summer not towing 150+
Summer towing 178
Summer under duress 200

These "increments" are roughly in 20 degrees rises. Ambient air temp does have an impact. Towing has an impact and towing under duress an additional impact.

Thanks very, very much. This is data. Real data. Much appreciated.

[gordon2]

One of many guides on the net.
Transmission temperature/failure chart.

Note that, to some extent, you can deal with occasional higher transmission fluid temperatures with more frequent fluid changes. Knowing how high the temp goes, and for how long, will give you an idea of how frequently to change the fluid. Any amount of time over 250-260 and I would be looking to change the fluid ASAP and looking to avoid a repeat. Staying under 200 makes me happy. Staying under 180 makes me even happier.

[DarrylScamp78]

I’m searching for OBDII Scanner / Code Reader that will read and display 2014 Highlander Automatic Transmission temperature while towing. All scanners I’ve found provide only engine specific information, NOT transmission.

[AlanKilian]

There's a lot of stuff on this thread that I don't understand, but you probably will.

https://www.toyotanation.com/threads...-temp.1525642/

[gordon2]

About 4-5 years ago I did that using the Torque smartphone app and a bluetooth OBD II interface from eBay.

https://play.google.com/store/apps/d...hl=en_US&gl=US

Things to know that were true then and are likely still true:

1. Toyota did not publish or share the OBD II codes with the public. It took quite a bit of digging around in online forums to find that someone had discovered the tranny temp codes and figured out how to translate the data into a real temperature. So one had to create a custom gauge in Torque and enter the given math formula. I was never sure that the data was accurate but it did seem consistent with what I expected to see when towing - expected increases and decreases when going up long grades, not using overdrive, hot weather, etc. IIRC there were two sensors also so which one was more important was a guess.

2. There were some compatibility issues with some bluetooth OBD II interfaces. IIRC the Torque developers had a list of sources.. but that was long ago.

And it appears that Torque might not be maintained like it used to be in which case there might be a different / newer app. Toyota forums would be a good place to research.

[ATHiker]

Originally Posted by DarrylScamp78

I’m searching for OBDII Scanner / Code Reader that will read and display 2014 Highlander Automatic Transmission temperature while towing. All scanners I’ve found provide only engine specific information, NOT transmission.

I use an Ultra Gauge OBD gauge to monitor the transmission temps (both pan and converter) in my 2015 Tundra. The codes that I am using also worked in my 2013 Tacoma. Not sure if they will read your Highlander tranny temps.