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Thread: using aftermarket temp. sensors on 7427 ecm's

  1. #1
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    using aftermarket temp. sensors on 7427 ecm's

    i am using a different temp sending unit than what came in the vehicle my ecm came out of...
    it originally had a 4l60e in it which has the internal sensor,
    and i am using a 700r4 in its place which this one does not have a temp sensor on it that i have seen.
    i ordered a sensor that will go into the pressure test port on the drivers side but i suspect it will give erroneous readings.
    if it does in fact give wrong readings, i was wondering if any of you know how to calibrate it.

    i am using bdyt as my starting bin.
    i have deleted the egr, and added the fan code for engine and trans fan control (you guys are awesome btw)


    Advanced $0D TP5 v251.xdf as the mask

    and use
    A217 $0D TP5 v250.adx
    A218 Trans1 $0D TP5 v250.adx
    A218 Trans2 $0D TP5 v250.adx

    to be able to see/log the data.

    the above files were obtained from this forum.

    from what i can figure there are several datastreams that the dashboard / data logging get their information from.
    can you display information from several datastreams on the same dashboard?
    is there a way to combine the adx files so that all the different adx values are available?
    how is the unique ID determined?
    how do you determine the "Packet Offset (H | D)"

    thanks in advance for your help.

    **edit to update that i am using 16196395 ecm ** i fat fingered the copy / paste
    Last edited by grumbolt; 03-01-2021 at 07:41 AM.

  2. #2
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    The tempsensor use ohm and gauge converts it to f or c (the gauge has 0-90 ohm need a sensor with 0-90 ohm).
    Diffrent values between senor, example1 has 0_-450 ohm other 0-90 ohm that can give errors.
    Idont now if you can change to values from sensor you have to the data logging program .
    Last edited by honken; 03-01-2021 at 03:16 PM.

  3. #3
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    thanks for the reply Honken, the sensor i have on the way may have the same specs as the oem 4l60e temp sensor.. i dont know honestly..
    if it does awesome and it is plug and play...
    i dont know specs on the oem i just planned on putting the sensor in water heated up to 190 degrees and seeing what the computer thought the temp was and going from there.

    if the ecm doesnt see an accurage temp, i was wondering if there was a way to change the "scale / formula" of how the ecm sees it.

    main reason for this is so i can run the $od fan mod that allows the ecm to control the engine and transmission fans based on their temperature

    i guess i could just wire it up and then change what the targets are. for example if it says it is 250 degrees when it is actually 150 degrees, then set the fan on to 250, and the overtemp to 275. (just numbers pulled out of the air would have to experiment to find real numbers) but if i did it this way, then the adx file would need to be altered to change how the data was displayed ..

  4. #4
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    Its over 10 years ago i hade 6395 ecm dont remember where i foud it,
    When i hade ecm to control a relay to the cooler fan, it read from ecms tempsensor.
    Pind some output that ecm didint used change adress in prom to read temp and did flag or table with temp to start and stop the fan.
    Had an ostrich dident have to burn a prom

  5. #5
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    Quote Originally Posted by honken View Post
    Its over 10 years ago i hade 6395 ecm dont remember where i foud it,
    When i hade ecm to control a relay to the cooler fan, it read from ecms tempsensor.
    Pind some output that ecm didint used change adress in prom to read temp and did flag or table with temp to start and stop the fan.
    Had an ostrich dident have to burn a prom
    i know the ecm is looking at pin B5 for a signal with B4 being ground.
    i guess my question is if i am using a temp sensor that isnt oem, can i scale it in the ecm to have it react the way i want it to and to display the correct temp when i am datalogging.

    for example, until the temp gets to 155F i want the fan to remain off.
    at 165F i want the fan to turn on.
    at 200F i want the fan to remain on. and the ecu to set the check engine light.
    when the transmission gets back down to 155F i want the fan to turn off.

    these temps will most likely end up being different, i will need to play with them to get it happy.

  6. #6
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    maby take the trans temp instead of engine temp
    For this you need a hack for adresses
    Last edited by honken; 03-02-2021 at 01:19 AM.

  7. #7
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    Quote Originally Posted by honken View Post
    maby take the trans temp instead of engine temp
    For this you need a hack for adresses
    i am not explaining my issue properly....

    the trans temp is input to the ecm on pins b4/b5 in its stock form.
    the oem temp sensor for the ecm would be what is found in a 4l60e and is internal to the transmission.
    the temp sensor i want to use (and will wire into the oem pins) mounts externally the resistance of the unit i will be using is 2158 ohms at 160, 1569 at 180, and 1160 at 200 all temps are in Fahrenheit
    if the new sensor differs from the old one, i was wanting to calibrate the ecm to the new one.

  8. #8
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    Okay you can set temp.
    found this https://ls1tech.com/forums/pcm-diagn...esistance.html

  9. #9
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    Quote Originally Posted by honken View Post
    Great info!! thanks much...

    just so i am not about to mess things up.... this is where i would adjust things correct?
    FAN ADJUSTMENTS.jpg

    edit to say i understand that i would have to edit the other places in the xdf and adx files to match....
    Last edited by grumbolt; 03-02-2021 at 04:24 AM.

  10. #10
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    this is the chart referenced in honken's post above..... clt-resistance-chart.gif

  11. #11
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    Is this only for trans fan ??

    You cant change parameter in editor this is what ecu use.

  12. #12
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    If it uses water temp you cant do anything.
    Cooling after engine temp is the most important.

    Aldl file maybe you can change the values ​​for gauge after your sensor 200f = ohm to oem ohm = f.

    If you use the gearbox sensor, it is your sensor temp f = ohm to oem ohm = temp in scalare.

    But I do not think it uses both sensors only one.

    If it is a own scalar whit different adress yes.

    But you need to know which sensor it uses and the right ohm at the right temp if it use gearbox sensor.

    I'm not so familiar with 6395 ecm anymore and how the code is written.
    Last edited by honken; 03-02-2021 at 04:23 PM. Reason: e

  13. #13
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    Quote Originally Posted by honken View Post
    If it uses water temp you cant do anything.
    Cooling after engine temp is the most important.

    Aldl file maybe you can change the values ​​for gauge after your sensor 200f = ohm to oem ohm = f.

    If you use the gearbox sensor, it is your sensor temp f = ohm to oem ohm = temp in scalare.

    But I do not think it uses both sensors only one.

    If it is a own scalar whit different adress yes.

    But you need to know which sensor it uses and the right ohm at the right temp if it use gearbox sensor.

    I'm not so familiar with 6395 ecm anymore and how the code is written.
    it is basically the same as the 16197427 (it uses the same xdf and adx files) as a matter of fact, the bin i am using in it is a 16197427 bin. it has a temp sensor for the engine located near the thermostat) as well as a temp sensor located inside the original 4L60E transmission.
    the temp sensor for the engine is on pins B3(ground) and B8(ECT signal).
    the temp sensor for the trans is on pins B4(ground) and B5(TFT Signal).

    not really sure where to find the actual address. the looking at the proper address part has already been taken care of with the fan mod i think. http://www.gearhead-efi.com/Fuel-Inj...Information-0D post#8

    pretty sure i just have to get the right raw value stored in the ecm (using the fan mod parameters) and everything should work...
    the parts should be here soon and i can set up a ecm on the bench and test my theory.. if it works the way i want it to, i will more than likely post up what i did to make it happy so others dont have the same issue i have .

  14. #14
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    Well, there's some good news and some bad news and some good news with work.

    The good news is that the coolant temp, air temp, and transmission temp sensors are not linear. These sensors all require a table (actually two tables for coolant and transmission temp) to convert the sensor reading into the correct value. In theory you should be able to enter the correct temperature values from your sensor and the ecm will use the lookup table to get the correct reading.

    Now here's the bad news: GM uses the same lookup tables for both coolant temp and transmission temp. So if you change them you will get the correct temp from the trans sensor and the wrong temp from CTS.

    The easiest answer might be to build new lookup tables and add them to an unused area in the chip. But that requires a little bit of coding skill. Another option may be to direct the IAT to use the CTS tables and to direct the TFT to use the IAT table. But the IAT table is very rough... there are maybe 5-10 values? Where the CTS/TFT tables are 256 byte tables.

    You might also be able to design a "best fit curve" that approximates the transmission temperature sensor values. We were able to do something like this for Tunerpro once we realized the conversion formula for CTS was producing errors. You may need to use a tool such as Excel to generate the formula then replace the table lookup routine in code with the formula. Probaably not as easy and not likely to be as accurate as creating new tables.

    A/D to Temp conversion tables are found at 0xF8eF and 0xF9EF. Transmission temp lookup and conversion begins at 0xC6F6.

    Good luck.

  15. #15
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    Quote Originally Posted by 1project2many View Post
    Well, there's some good news and some bad news and some good news with work.

    The good news is that the coolant temp, air temp, and transmission temp sensors are not linear. These sensors all require a table (actually two tables for coolant and transmission temp) to convert the sensor reading into the correct value. In theory you should be able to enter the correct temperature values from your sensor and the ecm will use the lookup table to get the correct reading.

    Now here's the bad news: GM uses the same lookup tables for both coolant temp and transmission temp. So if you change them you will get the correct temp from the trans sensor and the wrong temp from CTS.

    The easiest answer might be to build new lookup tables and add them to an unused area in the chip. But that requires a little bit of coding skill. Another option may be to direct the IAT to use the CTS tables and to direct the TFT to use the IAT table. But the IAT table is very rough... there are maybe 5-10 values? Where the CTS/TFT tables are 256 byte tables.

    You might also be able to design a "best fit curve" that approximates the transmission temperature sensor values. We were able to do something like this for Tunerpro once we realized the conversion formula for CTS was producing errors. You may need to use a tool such as Excel to generate the formula then replacing the table lookup routine with the forumla. Proabably not as easy and not likely to be as accurate as creating new tables.

    A/D to Temp conversion tables are found at 0xF8eF and 0xF9EF. Transmission temp lookup and conversion begins at 0xC6F6.

    Good luck.
    just a thought..... if i leave all the tables the same and use a bench setup to determine what temp the ecm "thinks" 160 degrees is. (lets say when the probe is at 160 degrees the ecm thinks it is at 300 degrees) couldnt i simply set the parameters in the fan mod to turn on at 300 instead of 160? i am only using the ecm to control the motor, the transmission is stand alone, and i am not even using TCC at this time. and if i do use tcc in the future, it will not be controlled by the ecm.

    honestly the coding is way over my head, i want to learn but that is going to be a long process lol... i dont know what the different commands are much less how to set up the tables into a usable format. i am very thankful for you guys that have pioneered the way for guys like me to be able to tune our toys without knowing the ultra technical coding stuff, we only have to learn the highly technical tuning stuff lol..

    thanks again for your help..
    grum
    Last edited by grumbolt; 03-03-2021 at 08:47 AM.

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