Custom PID transmission temp

I got the ELM327 bluetooth adapter for my truck and downloaded the Torque app. In order to get it to read the transmission temp I had to program in a custom PID. After alot of online searching and trial and error I think I have it reading the trans temp but I'm not 100% sure. I used the following inputs:

21d9
unit type: *F
equation: ((((E*256)+F)*(7/100)-400)/10)

Driving around for 15 miles with just me in the truck the reading I was getting went up to 160 degrees. I'm gonna try towing something today and see what it goes up to.

Are these the correct inputs for a 2009 4 cylinder ? It could be some random reading I'm getting but 160 sounds about right to me.

 

Get or borrow a Scangauge or equal. That will be your standard.

 

These are the codes that I use

 

160 sounds rights. What was the temp outside and what was the type of driving?

 

Outside temp was about 70. Country roads going 35-60 mph.

 

What do the letters in the equation correspond to ?
It seems if I try the 2182 code no matter what letters I use it gives an error message.

 

Here's what worked for me:

Once in Torque for the first time, setup your vehicle profile, which will enable you to start using the app.

From the main screen, hit your menu button, then choose "Manage extra PIDs/Sensors"

Hit the menu button again, and choose "Add custom PID"

Hit "OK"

Under the first item called "OBD2 Mode and PID" enter "21d9"

Under "long name" choose whatever you want. I typed in "Trans Custom"

Under "short name" choose whatever you want. I typed in "Trans"

Under "minimum value" leave it at "0" or type in "0"

Under "maximum value" type in "300"

Under "scale factor" leave it as "x1" or type in "x1"

Under "unit type" type in "F"

Here's the tricky part - under "equation" type this in, EXACTLY, without any spaces:

(((((G*256)+H)*(7/100))-400)/10)

That's *five* parentheses at the beginning! Just be sure that there are six total parentheses facing to the right, and six total to the left.

Leave the rest blank and hit "OK"

Now when you want to add a gauge to the display, you should see "Trans custom" or "Trans" or whatever you named it at the beginning.

 

I use basically the same formula, but A and B are my variables. Can anyone explain why it works, though?

Like what is the significance of (7% less 400) divided by 10? What is that factor?

 

And wouldn’t multiplying by -39.993 work just as well and be easier to type than ((7/100) -400)/10?

 

I have no idea man. I took that setup from someone who knows a whole lot more than me. There's gotta be some science-types on here that can explain it.

 

I think you must use G and H for variables, not A and B. I believe that these are words used by 21d9 PID for the AT converter temp sensor. Use same equation with variables E and F for pan temperature sensor. This seems to be working for me with temperatures starting at ambient air. Need to road test on Horton the friendly elephant, 2007 V6 4L 4x4.

 

So using this PID, when I change the transmission fluid I no longer have to put the truck in Check Temp Mode?

Also, for transmission fluid maintenance, do I use the AT converter temp sensor reading or the pan temperature reading?

 

could you tell me the difference between them 2 codes in your pic.? are they different sensors? so far i have found 3 codes for Transmission temp. they all give me a different reading. (In pic)

 

My understanding is that one is converter fluid temp and the other is pan fluid temp. Also this app doesn’t work on my phone anymore so if anyone has an updated version that works I’d love to get it working again.

 

Yeah im not sure.. What do you mean has an updated version? what kind of phone you got?

 

I got the same results and I assume that the only "reliable" trans temp value is the one you added as above.
Maybe the second gen has only 1 trans temp sensor?

I also wish that someone could verify that the formula is accurate.

I am about to change the oil before a long drive with a truck camper. I would like to monitor the trans temp.

 

So after running around with it only 2 of them 3 work proper. (bottom and right one are more accurate... i think) the top left one never fluctuated even from a cold start it was reading 130 whatever. the other 2 moved around alot. not in a bad way. they never read the same but if it is two different sensors... i guess it makes sense. I still didn't trust it to do the atf drain and refill. the obd wire jump is the route i went for the tempo check.

 

If you have an IR gun, you can use that to ID the pan temp reading. I have an UltraGuage that reads pan and torque temps. My IR gun reading on the pan is within 1-3 degrees on my UG reading for the pan. At idle, the pan and torque readings are very close.