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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #1 (Edited)
Alright I'll get to the Q in a few.

So a long while ago, I got the Torque Pro app for Android along with an OBDII bluetooth adapter, works great, but it didn't read transmission temps (which was the reason I got it, for towing). Well I've been doing some searching lately, and I used a custom PID (you enter it in the settings menu), this is the settings I used:

OBD2 Mode & PID: 21D9
Long Name: Transmission Temp
Short Name: Trans T
Minimum Value: 0
Maximum Value: 300
Scale Factor: x1
Unit Type: *F
Equation: ((((E*256)+F)*(7/100)-400)/10)
OBD Header: left blank

Not I'm not positive this is the transmission temp, but I think it is, this is where my Q comes in. I get a reading, and its acting a transmission would in terms of when it heats up. Heres the numbers:

Outside temp was 92*F
engine coolant was a steady 185'ish F
"transmission" temp was ~160ish driving steady. I got it up to 170 doing breif heavy acceleartion in 2nd gear. Then I hit rain and it dropped to 150F. When I was idling in my driveway, I read 165 for the temp, then I got out and using a thermocouple on a multi-meter read the temps on the actual transmisison. The pan was 150F, the cooler was 134F, and the side of the transaxle (from wheel well) was 155F.

I think that temperature is reading the output from the transmission before the cooler/radiator, and I think the rain dropped the pan/casing temp.

But to those who know trans temps, do those numbers look right?


edit: worth noting, from what I've read, the above only works with 08's. Later years (09+) have to use PID 2182, use A instead of E, and B instead of F.


edit: This is what it looks like in the app:
 

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6,463 Posts
From my moderate to limited knowledge of Trannys Yes that's completely normal.
They usually run 50 to 90 degs hotter than ambient temps,
depending on load, wind, ambient, etc....

As for the PID I will enter that into my phone and see what I get then connect up Techstream and compare what it says tranny temp is...
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #3 (Edited)
As for the PID I will enter that into my phone and see what I get then connect up Techstream and compare what it says tranny temp is...
Awesome! :thanks:

For awhile I wasn't sure if there even was a temp sensor as I couldn't find any reference to a serviceable sensor in the FSM. Until that post recently came up about a ATF temp warning light, I gave up looking.

I had never looked at ATF temps before, I just hadn't realized they would be that much lower than engine coolant temps. I had figured since it ran through the radiator, it would keep it closer to the coolant temp :dunno: But the casing temps don't lie I guess :D

edit: I did end up ordering a techstream thing off ebay :lol: Kinda bummed about the month shipping though... I want to be able to change my windows to lower when holding the key fob. After work in the afternoons, you can cook a chicken in my car since it sits in 100% sun all day :lol:
 

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OK bad news :(
I could not get the PID to work you gave me, I did edit it as said for my 2010
Triple checked it and it's entered correctly and Torque just says "no data" :dunno:
So I can't say much there :(

However let the HL warm up for 5-10 mins while laptop booted and connected,
then drove around the block twice to get fluid moving and

TIS says A/T Temp is 109.7 F
Ambient temp was 65 F so (Ambient 65F + 50F = 115F) or right where I would expect it to be when not towing :rockon:

Hope this helped some?

**ALSO I turned on the windows options and can't get it to work on mine :dunno:
This might be because I'm base model or may not work on any HL? :( :dunno:
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #5 (Edited)
Well shoot, I will say I tried 7 codes (all variations of that code) and that was the only one that worked. Well 2 turned up a negative temperature, I don't know about you, but I don't think the ATF is at negative 40 degrees :lol:

That sounds about like what mine did. It was like at 120*F (baking in 90-95 degree sun + I drove at lunch) when I left work and took a long time to get up to 170 on the interstate (20-30 min). In a month I guess I can confirm when I get techstream :lol:

Who knows about the windows, maybe its a smartkey thing? :dunno:

I appreciate you trying though, thanks!


edit: btw, all HL models have ATF routed through the radiator IIRC (I think most all cars have this now-a-days). Its only the air cooler that the tow package adds.
 

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AvConsult
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3,637 Posts
SP, I've never monitored trans temps. I thought the temp sensor was in the valve body? Most modern trans have a sensor as the ECU changes the shift timing, shift points, engine output and other parameters. The trans oil path through the radiator serves to both heat and cool the trans fluid, I'm told. There's no temp regulation mechanism, so no surprise trans temps vary quite a lot depending on ambient conditions.

I'm guessing the radiator cooler is sized to keep the trans fluid below a certain temp in the hottest weather and worst case engine heat output for rated load. For towing, the outboard cooler. In the Arctic for deep sub-zero weather, the trans may be luke warm or cool, as the engine thermostat limits coolant flow to radiator as ambient air rushes through radiator and over transmission, while the heater core(s) suck heat from the block.
 

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edit: btw, all HL models have ATF routed through the radiator IIRC (I think most all cars have this now-a-days). Its only the air cooler that the tow package adds.
Interesting, I did not know that....
I swore the tow pack` added coolant cooler.. hmm ok cool
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #8 (Edited)
SP, I've never monitored trans temps. I thought the temp sensor was in the valve body? Most modern trans have a sensor as the ECU changes the shift timing, shift points, engine output and other parameters. The trans oil path through the radiator serves to both heat and cool the trans fluid, I'm told. There's no temp regulation mechanism, so no surprise trans temps vary quite a lot depending on ambient conditions.

I'm guessing the radiator cooler is sized to keep the trans fluid below a certain temp in the hottest weather and worst case engine heat output for rated load. For towing, the outboard cooler. In the Arctic for deep sub-zero weather, the trans may be luke warm or cool, as the engine thermostat limits coolant flow to radiator as ambient air rushes through radiator and over transmission, while the heater core(s) suck heat from the block.
The sensor is in the valve body, I found it in a teardown pdf after making this thread, well its socket at least, its next to the filter/strainer on the VB.

Good thing I don't have to worry about deep sub-zero Arctic weather :lol:

Interesting, I did not know that....
I swore the tow pack` added coolant cooler.. hmm ok cool
It does, it adds this one:


edit: unless your refering to the engine oil cooler, it does also add that. But thats tucked under the front bank exhaust manifold.
Just to be clear, the tow package adds the trans fluid air cooler, engine oil cooler, higher capacity radiator,
roughly doubles the wattage of the cooling fans, and the 150A alternator.
 

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So is the engine oil in the coolant radiator too, and/or it just adds an air cooler for it on the tow pack`?
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #10 (Edited)
So is the engine oil in the coolant radiator too, and/or it just adds an air cooler for it on the tow pack`?
Take a look at the thread below. There is a seperate housing for the engine oil cooler. Both the oil and coolant is piped to it. There is a sticky for the engine oil cooler line replacement in the mod sticky. It will show it better than I can explain it.

http://www.toyotanation.com/forum/1...-prep-package-identification-information.html

The oil cooler and the trans fluid air cooler is only on the tow prep package. Non tow prep have atf lines going to the radiator, but no external piping/cooling for the engine oil

Sent from AutoGuide.com Free App
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #11
Yeah this is definitly the transmission I'm reading. Got in and it was reading 85 with the engine off after all night sitting (coolant was 86, the garage was hot). Slowly got up to ~150 after 20 min on the interstate. Climbed in a hury as I accelerated up a steep hill in 1st/2nd.
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #12
Alright update.

I got techstream yesterday, and while "exploring"/changing settings, I decided to look at the transmission temps. What I did was driving around to get the transmission up to operating temps. Pulled the temp via techstream, then immeaditely switched back to torque to pull the number from there, and they were within 1 degree F. So this is the transmission temperature I got.

Just to have a single post having all the information here is what I used on my 2008 (other years likely don't work from what I've seen/read):
OBD2 Mode & PID: 21D9
Long Name: Transmission Temp
Short Name: Trans T
Minimum Value: 0
Maximum Value: 300
Scale Factor: x1
Unit Type: *F
Equation: ((((E*256)+F)*(7/100)-400)/10)
OBD Header: left blank

Now that I can monitor the temps, I'm seriously considering installing a 2nd auxiliary cooler (an additional one beyond the OEM one). Driving on the interstate in 92 degree weather at 70mph in 5th gear, it was a steady 170-172F. In city driving it was 180-185F. That is a LOT higher than I would like to see when not towing. I haven't towed a heavy trailer yet (I've towed an empty cargo trailer, but it was so light, it wouldn't have an impact), so I'll hold off until I see actual heavy towing numbers. Considering how much temp impacts ATF life, its very likely I'll go that route though... :facepalm:
 

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Now that I can monitor the temps, I'm seriously considering installing a 2nd auxiliary cooler (an additional one beyond the OEM one).
I would not do this! That fluid is meant to run at a certain temp, and cooling it beyond what the engineers have deemed acceptable may give you problem later. I know that temp is what kills transmissions, BUT if your transmission isnt leaking, etc, then youll probably be fine. You also have to remember that the line pressure in the transmission is very important, now the cooler line doesnt run high pressure, BUT the added resistance, and length of travel time back to the pan, may cause other issues, IDK? You also have to remember that certain trans need certain temps to shift properly. I have noticed that when its really cold out, my transmission will not allow me to accelerate rapidly until the vehicle comes up to temp, so Im assuming that this tranny requires the temp to be in a certain range for the computer to shift it properly.

OH wait this is Sweeneyp we are talking about:thumbsup:
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #14
:lol:

I didn't say I was going to get it, I'm waiting to see. Only way I'll get it is if I see temps approaching or going over 220F while towing a heavy trailer. Otherwise I'll leave it.

IF I do get it though, it would be a simple tube and fin cooler. Those should flow much easier than a plate and fin (OEM type, its more of a radiator design). Plus from what I can tell, they don't cool as well as plate and fin ones so its a win/win. I don't want a massive drop in temps, just a small'ish one, and as the trans temp gets higher, its effectiveness will become greater (as the delta T increases). Specifically this one: https://www.etrailer.com/Transmission-Coolers/Derale/D13220.html My plan would be to install it behind the lower bumper air intakes (that way its not sitting in front of the radiator/condenser like most other transmission coolers.
 

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Resident Nutcase
'08 Highlander Limtd
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12,177 Posts
Discussion Starter #16
Could, only thing is there ins't much airflow there. There is zero direct air flow at least. Toyota uses ducts to redirect air from the fog inlet and the splash guard inlet to the cooler. Oh well, we'll see next time I tow :dunno:
 

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2008 Highlander
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Interesting thread. Wish I had an Android phone to try this with, mine's an iphone.

My '08 HL (Base, w/tow prep package) never used to light up the trans temp light before, but this July it came on 4 or 5 times during my trip between OK and Yosemite. This despite having the trans fluid changed (and front transfer case resealed) just a month before this trip.

I took the HL in to a local dealership upon my return, and explained this to them. I asked them to look and see why it would be getting hotter than before (under similar conditions: same trailer, similar grades, similar weather, similar speed). I even asked them to inspect the cooler fins to see if they were really dirty or something.

They discovered some fluid leakage (pan gasket and LF axle seal, the latter they think the mechanic may have nicked when reassembling after resealing the front transfer case), but did not say how low the fluid was or if that could have caused the temp light to come on. In fact what they wrote on the bill was: "No problems found. Light came on for safety of the trans. Getting to hot." (sic) Those comments seemed remarkably unhelpful. Of course it's getting too hot! The question of "why" was not addressed. (Makes me wonder about the quality of communication between service advisors and mechanics.)

One time the light came on stands out in my memory. It was the grade climbing east out of Albuquerque, which is not extremely steep but is fairly prolonged. Weather was damp (recent rain and cold front) with outside temp around 70 degrees. I was running in 3rd gear (4 & 5 locked out) at about 60-62 mph, towing a 2700 lb, 7' wide trailer. After a few miles of gradual climbing, the light came on and the tranny kicked into 5th gear on its own.

When it was newer, I believe the HL could have done that hill in 95 degree weather without the light coming on. Now at 150K miles it was a different story.
 

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I know I'm reviving a very old thread but it is directly related to my question.

A little background info..... I'm currently driving a 2011 HL with tow prep and towing about 2800 pounds. The time is approaching when I'll be looking to replace it with something newer and I am torn between the Jeep Grand Cherokee and the 2017 / 2018 HL. Uncertainty about reliability aside, the Cherokee has a vast array of displayable parameters appropriate for towing such as coolant, oil and transmission temperatures and overall is a nice vehicle. And best of all, it is readily available (plentiful, actually) in the color and configuration I want. After driving both, I still prefer driving the Highlander and in a perfect world, that is what I would get. But it is essentially impossible to find anywhere in the color and configuration I want (Salsa red, FWD LE Plus). But if I CAN find one, I would really like to be able to view the transmission temp while towing, so I read this old thread with interest.

So..... do any of you know if the transmission temp is available on the Gen3 HL via OBD2? I have looked at a couple aftermarket gauge packages and they don't list trans temp as one of the available displays but it sounds like you guys were able to view it on the Gen2? What about Gen3? If I can actually find the HL I want, adding an OBD2 display would give me the best of both worlds.

Paul
 

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2001 Avln, 2009 Taco
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254 Posts
My apologies for reviving an old thread...

I just bought an OBDLink MX Bluetooth OBD2 adapter. I have been trying to display the TRANSMISSION TEMPERATURE with both the OBDLink app and the Free version of Torque with no success. While I have been able to add the PIDs to both apps, I get no data drom the vehicle. I have tried both the 21D9 (E, F, G and H) and 2182 (A, B, C and D) OBD2 PIDs and get the same result. I have even tried to mix & match addresses and variables; i.e. 21D9 (A, B, C and D).

The vehicle in question is a 2009 Tacoma with a 4.0L and 5 speed automatic.

Any ideas?
 

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This is the EXACT formula that is confirmed to be working on my 2011 Limited AWD:

PID: 2182
Long name: Transmission Temp
Short name: Trans T
Minimum Value: 0
Maximum Value: 300
Scale factor: 1x
Unit Type: *F
Equation: ((((A*256)+F)*(7/100)-400)/10)

This formula may work for other years but it for sure works for 2011.
 
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