## Forums

#### Guest

Welcome Guest, posting in this forum require registration.

 Pages: [1] 2 3
Author Topic: Help with Tacoma transmission temp
Krookz
Member
Posts: 6
 Help with Tacoma transmission tempon: January 5, 2012 (GMT)

Hey. Iv been trying to convert the Scanguage values for the Tacoma trans temp into PID, ect, to use in Torque. I cant seem to get it right. Anyone else try this and have any sucess? The two methods in Torque dont work. We’re trying these on 05+ Tacoma’s

http://www.scangauge.com/support/toyota-specific/
General Toyota (CANSF)
GAUGE TXD RXF RXD MTH NAME Notes
Transmission Temperature 07E021D9 032180000000 2810 00070064FE70 TFT Degrees F

OBD2 PID: 21D9
Long Name: Tacoma Trans Temp – Auto
Short Name: Trans
Min Value:
Max Value:
Scale Factor: 1
Unit Type:
Equation: ((A*256)+B)*(7/100)-65136

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 5, 2012 (GMT)

We’re working on this over on tacomaworld forums as well.

After a quick re-read of the thread here http://torque-bhp.com/forums/?wpforumaction=viewtopic&t=352.0 on the conversion process, we’ve updated the equation to:

((A*256)+B)*10*(7/100)-400

But it still seems to be notably high (I doubt my transmission is 5000 degrees F)

I’ll update this thread if I learn anything new

Krookz
Member
Posts: 6
 Re: Help with Tacoma transmission tempon: January 5, 2012 (GMT)

Im on TW

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 5, 2012 (GMT)

Quote from Krookz on January 5, 2012
This is ruggedT on TW

Heheheh. Let’s hope someone on this board knows more than we do!

piemmm
Posts: 6629
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

You’re close, I think.

the 65136 is wrong, it’s a signed value (with that bit set) so it’s -400, not 65136

-400 is an interesting number, mainly as temperature readings over OBD2 are usually given in C (not F) even for extended PIDs – most of the OBD2 PIDs for temperature are A-40

So you may be looking for something like:

((((A*256)+B) * 7) / 100) – 400

LGE RAW
Member
Posts: 11
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

I’ll test this with the following custom PID info:

21d9
TFT
0.0
300.0
x1
F
((((A*256)+B)*.7) / 100) – 400

Will post what the result is soon.

Rob

LGE RAW
Member
Posts: 11
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

I connected to my ECU with the ignition switch on an engine off and hit the test button with the following result:

Results for equation: -400
Command: 21d9
Response:00A
0: 61D900000000
1: 384038E0000000

In the 1: reply, the 4 changed back and forth to an E.
Outside temp was 68 degF. Initial TFT reading was -400.
When is started the engine, the TFT temp changed to -352. I then took the readings at the following engine temps:

Coolant: TFT:
100 -360
130 -366
150 -371

after 5 mile drive to warm up everything, idling in park:
185 -371.3

Hope this helps with figuring out the issue.

Rob

Krookz
Member
Posts: 6
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Awesome! Thanks alot. Ill check this on mine later

LGE RAW
Member
Posts: 11
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

I’m not sure why it is returning a negative value. I think the fluid temp should be between 150 and 200 degF else it would burn the fluid.

Krookz
Member
Posts: 6
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Yea. The FSM states it should be -40°C to 215°C (-40 to 419F)

1) There are two temperature sensors in the 09 AT, “A” and “B”. They read the oil temperature, as one would expect
2) The sensors present the temp as an electrical resistance to the ECU, varying from 79? to 156k? and the ECU converts it to a temp value in °C
3) The Toyota Techstream tool reads the temps from the ECU through the OBD interface, so it must possible for us to do so, too!
4) The ECM speaks ISO 15765-4 (and possibly SAE J1987, they’re both mentioned in the manual)
5) The “B” sensor is placed directly before the oil cooler inlet pipeline, not mentioned where the “A” sensor is
6) The ECU considers the valid temperature ranges to be -40°C to 215°C (-40 to 419F)

LGE RAW
Member
Posts: 11
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Is the response returned in ohms or degrees?

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

I just tried this over lunch, too, and got similar results. Negative values for a while, then some rather small positive numbers after warm up.

I noticed you took out the *10 modifier, I might try putting that back and seeing if it makes more sense. Seems like we’re getting closer!

Krookz
Member
Posts: 6
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Quote from LGE RAW on January 6, 2012
Is the response returned in ohms or degrees?
Its returned as *C

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Quote from LGE RAW on January 6, 2012
Is the response returned in ohms or degrees?

That’s the oddball part – the hex values returned in the response (using the Test feature in Torque) don’t seem to be either, but then again we can’t tell what they really mean. If we interpret them as IEE754 floating point values, we get like 117 for the 0: value. They’re insanely high if read as integers, so I’m thinking they are floats, but we don’t know the scaling for sure. Automotive controller programmers seem to have their own standards for things that don’t always jive with other types of automation software or even general personal computer standards. One of the fellows on TacomaWorld and I have been trying to figure out what ISO spec is being spoken so we can try to track down what scheme floats use in that world, but with no real success so far.

piemmm
Posts: 6629
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Most of the temperature conversions I’ve seen are:

A-40

(((A*256)+B) / 100)-40

((A*256)+B) / 8

All measured in Degrees C.

It would be interesting to see the results from the ‘Test’ button with the engine running and a ‘cold’ transmission (ie: let to cool to ambient overnight). (the test result quoted above was all 0’s which likely means you need the engine running before you get readings from the transmission)

It would then be reasonably trivial to see where the issue is with that gem of information

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Quote from admin on January 6, 2012
(the test result quoted above was all 0’s which likely means you need the engine running before you get readings from the transmission)

It would then be reasonably trivial to see where the issue is with that gem of information

Interesting… so here’s what I’m understanding:

Eq result: -400 (means the A and B were 0 to get that result)
Response: 00A (I assume is just an OK message)
0: 61d912000000
1: 51E053C000000

So the two pieces of hex data are not A and B? Or are A and B just some portion of the lower bits of those values? I guess I’m just really quite confused as to where A and B come from

LGE RAW
Member
Posts: 11
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

It has been several hours since I shut my truck off. I need to pick up some plugs for my wifes Sequoia, so i will get the test info at the current temp using the equation above.

If you have another equation to try, let me know.

piemmm
Posts: 6629
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

A and B are the values immediately after the 61d9 part of the reply – ie the 0000 (which would be A=0x00, B=0x00, C=0x00 and so on…)

0: 61d912000000

which A=0x12(hex) and B = 0x00

where A would be 18 in decimal and B would be 0

which in the equation would be: ((A*256)+B) = 4608

(I’m assuming this reading was taken at ambient temperature for your transmission?)

psychohamster
Member
Posts: 16
 Re: Help with Tacoma transmission tempon: January 6, 2012 (GMT)

Ah! That’s the part that’s been driving me nuts! So A and B are integers, and they’re both packed into the last few bits of the first param. The second param is a red herring…

Yup, the hex values I wrote down yesterday with my truck at idle after having left it alone for about 6 hours.

piemmm