OBD Fusion + Bluetooth Scanner = Pretty Neat!

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
I picked up a $35 bluetooth scanner on amazon, and I bought the $10 ODB Fusion app on the iOS app store. It's pretty cool. I like how I can make my own little mini dashboards. I've been playing around with all the PIDs. Many work, like speed, instant fuel-economy, throttle position etc. Many did not.

I'm sure many of you are using this exact same system. What are some cool things you've been able to do with it?

The main reason I bought this was to read error codes when the engine light comes on, and to get a transmission temperature gauge I can use while towing. I haven't had any luck finding trans temp though. Is it in there somewhere?
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
I picked up a $35 bluetooth scanner on amazon, and I bought the $10 ODB Fusion app on the iOS app store. It's pretty cool. I like how I can make my own little mini dashboards. I've been playing around with all the PIDs. Many work, like speed, instant fuel-economy, throttle position etc. Many did not.

I'm sure many of you are using this exact same system. What are some cool things you've been able to do with it?

The main reason I bought this was to read error codes when the engine light comes on, and to get a transmission temperature gauge I can use while towing. I haven't had any luck finding trans temp though. Is it in there somewhere?

What year is your vehicle? And do you know if it uses a CANBUS or the single wire J1850VPW protocol? A look at the OBD2 port will tell this. If there are only 4 terminals seen inside the connector then it is the J1850VPW, the CANBUS would have 6 I think.
 

Mooseman

Moderator
Dec 4, 2011
25,662
Ottawa, ON
08+ does use CANBUS. I had to reconfigure my benchtop setup to program one to work with CANBUS and add the extra wires to the connector.
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
If I ever see an 08 in the Upull I'm going to grab the TCM/ECM/PCM to scan for PIDs and see what I can do there. Of course that's an entirely different message structure and I'd be starting the learning curve from the near bottom.

The reason I asked is we have a bunch of PIDs we know work on earlier models, albeit with a different PCM, and also the Torque Pro app comes with some that just might work. OBD Fusion doesn't offer these but it is possible to add them as custom PIDs. So things like the transmission fluid temperature just might be in reach. I have a bunch of stuff added that way in my OBD Fusion app.

There is another thing I'd like to try on an 08. They do run CANBUS but they also run J1850 for I think everything but the TCM I think.

So in theory it should be possible to use either protocol with the EML327 dongle but I don't know what would be availabke on the J1850 from the ECM.

So many questions...
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
QUESTION:

Are any of the pins on this connector powered when the car is off?
My battery has been weak since getting this device. I had left it plugged in since I got it. I'm wondering if it's a coincidence and my battery is dying, or if this device is draining my battery.
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
QUESTION:

Are any of the pins on this connector powered when the car is off?
My battery has been weak since getting this device. I had left it plugged in since I got it. I'm wondering if it's a coincidence and my battery is dying, or if this device is draining my battery.

Yes. Bottom row far right is terminal #16. Always powered. If the device is left in it is possible for the device to draw a small amount of power. What can draw even more power is if the device is in range of your phone or tablet and occasionally links up via bluetooth the app like Torque Pro, OBD Fusion etc may attempt to connect in the background and this can cause the vehicle network to remain in wakened state instead of sleep mode. This will surely run down a battery.

One more caution. Most all of these bluetooth devices are insecure, meaning anyone who desires to can link up their phone to it. I don't imagine there are a whole lot of people who know how, but I could unlock your vehicle if the device was left plugged in :wink:
 
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Mooseman

Moderator
Dec 4, 2011
25,662
Ottawa, ON
And it's powered by the lighter plug fuse so always on.
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
Well thats good to know. The lighter plug has also screwed me over. Before I installed real heated seats, I had a heated seat pad that would stay running when I got out of the truck and sever times I'd go to leave work appointments and nada. I was very tempted to do some custom wiring to make that power switched on and off with the truck itself. Which actually would have been helpful now that I think of it because my USB charger also tends to drain my battery. Oh well.


Also, back to the more fun topics of PIDs, does anyone know the id for transmission temperature? Having a gauge for that while towing would be very nice!
 

azswiss

Member
May 23, 2021
949
Tempe, AZ
Here are a couple that you can try:
Long Name: [GM]Transmission Fluid Temp (GM Method 1)
Short Name: Trans.Fl.Tmp1
Mode/PID: 221940
Formula: A-40
Min: 0
Max: 200
Units:°C
Header Auto
Scale: x1

Long Name: [GM]Transmission Fluid Temp (GM Method 2)
Short Name: Trans.Fl.Tmp2
Mode/PID 221940
Formula: A-40
Min: 0
Max: 200
Units: °C
Header: 7E2
Scale: x1

Long Name: [GM]Transmission Fluid Temp (GM Method 3)
Short Name: Trans.Fl.Tmp
Mode/PID: 221949
Formula: (A-40)/0.75
Min: 0
Max: 200
Units: °C
Header: Auto
Scale: x1

Edit: Corrected Header for GM Method 2 (from 700 to 7E2)
 
Last edited:
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TJBaker57

Member
Aug 16, 2015
2,963
Colorado
Long Name: [GM]Transmission Fluid Temp (GM Method 2)
Short Name: Trans.Fl.Tmp2
Mode/PID 221940
Formula: A-40
Min: 0
Max: 200
Units: °C
Header: 700
Scale: x1

Edit!! I looked back and see you DO have a canbus vehicle. So with some fixing of the header as noted below it "might" work.


This one won't work except possibly for CANBUS vehicles and with a small correction. The correction is needed due to Google Sheets and other spreadsheets insistence on altering data as it is imported. The original header field value was "7E2" which is an identifier for an ECU on the ISO 15765-4 bus. The spreadsheet sees this and believes it is an exponent! So it changes (corrupts) the data.

Somewhere I have a file of PIDs for import to OBD Fusion. Each app has its own way of writing equations and not all apps have the same functions available.
 
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l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
So I had the idea that I could get a big gauge on one page that would show the throttle percentage. By throttle though, I didn't mean in the engine, I meant on the gas pedal. In otherwords, how much gas are you giving it. My truck doesn't feel fast at all but most people don't realize that i'm practically idling every where I go. Once I actually give it some decent input, it takes off.

So I found a bunch of throttle related options, but they all seemed to be different, and none seemed to be what I wanted. The screen shot was taken with no put on the gas at all, just idling. Is there a way to get what I'm looking for? Which would be a gauge that says 0% when your foot is off the gas and 100% when you floored it?
 

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TJBaker57

Member
Aug 16, 2015
2,963
Colorado
My post #4 over here shows most of what is available. There is an APP average near the bottom center in the picture. That may be what you are looking for. There are two sensors for the accelerator pedal and each of them could also be used I suppose.


Here are the particulars for adding this to OBD Fusion...

Screenshot_20220202-065659.pngScreenshot_20220202-065722.png
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
I'm sitting here trying to add the transmission temp custom PID and I cannot figure it out. I was praising this app when I first got it, but the more I use it, the most half assed it seems. Like the interface was just thrown together in a hurry without given any real thought to.

But anyway, how do you add a custom PID? All I see are search boxes, no place to actually input one. Even when I click on User-Defined PIDs in the menu, all I get on the following screen is a search box.
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
I'm sitting here trying to add the transmission temp custom PID and I cannot figure it out. I was praising this app when I first got it, but the more I use it, the most half assed it seems. Like the interface was just thrown together in a hurry without given any real thought to.

But anyway, how do you add a custom PID? All I see are search boxes, no place to actually input one. Even when I click on User-Defined PIDs in the menu, all I get on the following screen is a search box.


Are we talking about the same app??

Screenshot_20220207-211058.jpgScreenshot_20220207-210901.jpgScreenshot_20220207-210943.jpgScreenshot_20220207-210954.jpg
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
Yes same app but I was in a completely different screen. I copied your info and I'll test it tomorrow when I'm in my car. But why did you name your sensor "app average"? What does that mean?

And is that info to make a throttle gauge or to make the transmission temp gauge.

Also how do I try adding the PID's from this post: #11
The info listed doesn't match up with the PID editor screen. I feel like I'm missing something?
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
But why did you name your sensor "app average"? What does that mean?


The name reflects what the PID is called by the Tech 2 scantool. Accelerator Pedal Position Average. Understand that the name is a user choice item, you can name a PID by any name you wish. It helps to keep the name the same as or similar to what others name it so when discussing a given PID you all know what PID is being discussed. The accelerator pedal and the throttle each have two sensors. I suspect the APP Average PID is a short-timed average of the position of pedal.



As for why the details of post #11 don't match OBD Fusions editor is that post #11 is using the nomenclature of the Torque Pro app and it won't necessarily match exactly with what other apps use for naming conventions or options.

It helps to have an understanding of what the essentials are. When the PID information is sent to the PCM or whatever there are 2 essential pieces of information. The first is "mode" (whose name was changed like 20 years ago to "service" but nobody uses that name). A module such as a PCM offers several different "services" (modes) of operations. Here are some of them. Note service #22 ...

Screenshot_20220208-082550_Chrome.jpg

The second piece of information is the specific PID you are requesting, a 4 character value. Torque combines both of these two items into one field where OBD Fusion keeps them separate.

There are some legislated PIDs used primarily for emissions testing that must be the same across all vehicles. These are primarily service (mode) 01 PIDs. We are interested mostly in service (mode) 22 PIDs. These are proprietary information and not required to be published so most of what we see online is stuff that enthusiasts have discovered and may or may not be correct. These PID values will not always be the same from one model of vehicle to another but some may be the same across different models.


And is that info to make a throttle gauge or to make the transmission temp gauge.

The screenshots I posted are for accelerator pedal position average as the name implies. Post #11 contains transmission fluid temperature possibilities. The first set of values in that post is the likely one for pre 2008 GMT360/370 Vortec 4200.
 
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TJBaker57

Member
Aug 16, 2015
2,963
Colorado
I neglected to explain why in the screenshots I posted for the APP Average PID, the PID entry is 12b001 and not just 12b0.

Some GM PIDs require further optional parameters before they will respond. The Torque Pro app will try different things in the background to get a reponse so if you enter just 12b0 for this PID the first attempt by Torque will receive a negative response from the PCM and then Torque will start trying different things to get a positive response. One of these things Torque tries is the addition of the "01" after the actual 4 character PID value. I find it faster to just do that part myself.

Another thing I left out was any mention of the "Header" field. A "header" is a portion of a message sent before the service (mode) and the PID value. The PID entries we are using here have a 3 byte header that describes the kind of message we are sending, how important is the message, who is the intended recipient of the message, and where to reply to the message. OBD Fusion only requires that you input one of their supported acronyms like ECM or ABS and it will construct what it believes is the appropriate 3 byte header. For advanced users there is an undocumented way to specify the exact 3 byte header yourself but we don't need to do that here.

As an aside, in Torque there are also supported acronyms or you can enter "Auto" and Torque will try several things trying to get a response. The things Torque does are never seen by the normal user but I have monitored the data stream and have seen some very weird messages. Torque is good at getting a response because it keeps trying different messages but some of these attempts are truly odd. Torque will start mixing up custom headers from one PID definition with PID definitions so where I have custom PID definitions for many different modules this mixing up message parts produces messages such as requesting the engine oil temperature from the liftgate module!
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
My transmission may be shifting a little funny, or it may just be in my head.
Is there a way to get a gear display to show what gear I'm in, and whether or not the torque converter is locked?
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
My transmission may be shifting a little funny, or it may just be in my head.
Is there a way to get a gear display to show what gear I'm in, and whether or not the torque converter is locked?


Well,,, maybe. In 2008 they started using a different network protocol and I don't know squat about that one.

The Torque Pro app has a few PIDs that might help and it is likely these can be added to OBD Fusion as well. "Current Gear" and "TCC Slip Speed" come to mind.

In your build thread you spoke of wanting a tune to address sloppy shifting. Was this ever done or are you still running factory settings?
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
I did get it tuned and it did seem to have an effect for a while but it seems like the tune has "undone" itself over time. After the tune, I could give it just a little extra throttle on the highway and it would instantly drop down a gear. Made the truck so much more responsive on the highway. But this has completely gone away. The other noticeable feature of the tune was that the duration of shifting gears was sped up. I haven't driven any other GM trucks in years so without something to compare to, I couldn't really say if that aspect is still "tuned" or if it has returned to stock.
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
Question: Can you look up check engine light/error codes with this device?

If you mean can you read the alpha-numeric DTC codes from the vehicle, then yes. Either with software apps meant for that purpose and more or also by use of a serial terminal app where you do the asking yourself. Got a specific issue in mind?
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
@l008com

Here is something to try for transmission fluid temperature. Let me know if this works and if it doesn't then show what you get when you hit the "TEST" button in the PID editor.

Screenshot_20230317-084010.png
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
I'll try this out later. Can you explain the A-40 equation? I don't understand that one. Are the raw thermal sensors returning C or F? Based on that equation, it looks like they return F + 40° but that doesn't make sense??
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
I'll try this out later. Can you explain the A-40 equation? I don't understand that one. Are the raw thermal sensors returning C or F? Based on that equation, it looks like they return F + 40° but that doesn't make sense??


Most all automotive sensors natively return values in SI units or SI derived units. So temperatures are natively degrees celsius.

Many Apps have a setting that will do the conversions for you before displaying the values on a gauge in a dashboard.

For example I beleive Torque Pro has such a setting and then PIDs whose definition states the value is in °C will be converted to °F by Torque Pro for display if the user has made such a selection in settings.

Sometimes you will see the conversion done in the equation. In this case the PID definition should state the units are in °F so Torque Pro won't apply the conversion a second time rendering an incorrect value for display.

All the sensor data and indeed most all the serial data is in hexadecimal. In basic hexadecimal there are no negative values. No fractional values either. One bit, two bits, three bits, but no half bits and no negative bits.

So how do you transmit in hexadecimal a temperature value in the negatives? You add an offset value to it that you can then subtract later after the conversion from hexadecimal to decimal.

I cannot claim to know why they chose 40 as the offset for temperature values. Might have something to do with the fact that -40°C is equal to -40°F??

The letter "A" is called a 'token' that Torque assigns to the first data byte in a message. The second data byte is "B" and so on.

So "A" in a Torque Pro equation the is the decimal equivalent to the first hexadecimal data byte in a PID response message.

Lets say your transmission fluid temp is -10°C.
The PCM will add 40 decimal to this making it 30°C so there is no negative value.
30 decimal is 1E hexadecimal. The PCM sends this 1E back in response the the PID query.
Torque Pro or OBDFusion will convert this hexadecimal 1E to decimal 30 and assign the token "A" to this value.
The equation or formula for the PID will subtract the 40 offset from "A" (which is 30) to arrive back at the -10°C we began with.

If the user has selected to have Torque Pro or OBDFusion to display temperatures in °F instead of ° C and the PID is defined as °C, then the app will do the conversion for them when the value is displayed in a dial or gauge on a dashboard.

Clear as mud right??
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
That actually does make sense to me :smile: I'm a software dev of sorts and I've done stuff like that, changed the range of a set of numbers so they better fit an sql data type so the overall database will be smaller in size. It just seems too clever for GM to do :biggrin:

And they probably go with -40 is the lowest possible temp because it doesn't get colder than that very often, most places on earth.

As for this setting, it actually worked in ODBFusion! It's a bummer what a bad user interface this app has but if you jump through enough hoops, you can actually get some data! So it started at around 11, and got up to I wanna day 22. It was only a half a mile ride, so those numbers do add up if you convert to F. So all I need to do is adjust the formula to also convert to F and I should be good to go, finally! It will be interesting to see what my typical transmission temperature is, and then what it is when towing trailers of various weights.

Hopefully I can get similar success in my TPMS thread.

Speaking of that, I'm also interested in setting up the TPMS monitors in ODBFusion like you did in this post #15

But how do you do it? It is unclear from your post how you set that up. At first I assumed those four ID numbers were the PIDs, but PIDs can only have 4 digits it looks like?
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
So all I need to do is adjust the formula to also convert to F and I should be good to g

Try this, in OBD Fusion open settings, preferences, units, then set temperature to °F.

Then in the PID editor check to see what are the "units" selected. I'm sure there must be a way to have OBD Fusion do the conversion. Try setting the PID editor units at °C and the units preference in sett8ngs to °F.

Otherwise the conversion is pretty straightforward. °C * 1.8 + 32 = ° F.
 
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TJBaker57

Member
Aug 16, 2015
2,963
Colorado
you mean (A * 1.8) - 8
Yay math!
Well not really. Take my example from above. The temp is -10°C. The PCM adds 40 for the offset yielding 30. Torque tokens this as A. Substitute 30 for 'A' in your expression...

(30 * 1.8) - 8 = 46°F

The real value equivalent to -10°C is 14°F.
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
Oh I meant to say boo math. I knew something was up because while I am getting some reasonable F values, sometimes I'm not. I started the truck up when it had been sitting for hours and it immediately read 95°F instead of the 55° or so it should have.

((A-40)*1.8)+32

So that should do it, right? I was too eager to simplify
 

TJBaker57

Member
Aug 16, 2015
2,963
Colorado
I started the truck up when it had been sitting for hours and it immediately read 95°F instead of the 55° or so it should have.

((A-40)*1.8)+32

So that should do it, right? I was too eager to simplify


So I have done some research on OBD Fusions way of doing things and I think I have this figured out.

3 options...

First option; you can leave OBD Fusion at defaults and use the equation as you post above, though it has one extraneous set of parentheses, it will work. In the PID editor enter both "Metric units" and "English units" as °F. These two fields are merely the text you want displayed on a dashboard gauge, nothing more significant and do NOT affect any calculations. And since you are doing the conversion to Fahrenheit here in the equation you want to be sure the display label always reads "°F". Leave the scale factor and offset at the defaults of 1 and 0 respectively.

Second option; do the same settings as above in the first option but use the equivalent equation "A*1.8-40". I will leave you all to scratch your head, a**, or both and figure out why that equation is equivalent to the equation in option 1.

And lastly option 3; Here is where the real work of figuring out how to get OBD Fusion to do the conversion happens. I mentioned earlier that there should be a means of having the app do the conversion and there is. So starting with the user-entered PID editor, In the two fields given for "Metric units" and "English units" enter the label you want displayed in gauges you place on a dashboard. This is only a label, nothing more. Below that enter values for minimum and maximum values. I didn't test this but I think these are not actual limits but maybe used as defaults for gauges layouts? At any rate I think you can put just about anything here. Now then, in the field for "Metric to English Scale Factor" enter "1.8" (without the quotes seen here). Next up in the field " Metric to English Offset" enter "32" (no quotes). The next few fields should be left as you had them for a 2008, header=@7E2, mode=22, pid=1940. NOTE: for the pid you may need to use 194001. I need to do this for my 2002, 2003, 2004, etc P10 PCMs.
Set the equation to A-40.

You're not done yet.... Exit the PID editor and back at the home screen open Settings, then Preferences, then Units. See the selection for "temperature" with a choice of °C or ° F ??? IGNORE THAT!! Instead, scroll all the way to the bottom and find the selection for "other" with the choice of "Engish" or "Metric" and set that to "English".
Evidently, the choice of measurement display seen up near the start of that "units" list is only for the built-in SAE pids and all the user-entered pids come under the selection of "Other". This is why we have the fields for English and Metric scale and offset values in the user-entered-pid editor.
Screenshot_20230319-094555.jpg


Screenshot_20230319-094624~2.jpg

Screenshot_20230319-094632~2.jpg

Screenshot_20230319-094638~2.jpg
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
Yikes, given how crazy option #3 is, I'll gladly stick with option #1!
Also I don't understand why option #2 works, that doesn't seem to make sense.

So with the current setup, I should be good to go. I'll test it out next time I go for a drive and we'll see how it goes.
 
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TJBaker57

Member
Aug 16, 2015
2,963
Colorado
Yikes, given how crazy option #3 is, I'll gladly stick with option #1!
Also I don't understand why option #2 works, that doesn't seem to make sense.

So with the current setup, I should be good to go. I'll test it out next time I go for a drive and we'll see how it goes.
The only real setup difference between #1 and #2 is the equation.

Option #2, the A*1.8-40 equation works because without subtracting the offset before the multiplication you have an "extra" 40*1.8. That comes to 72. Now you were going to have to add 32 to the product anyway, and the difference between 72 and 32 is 40. So you just subtract that difference. At least this is ONE way to look at it.
 

l008com

Original poster
Member
Feb 19, 2016
919
Massachusetts
So I don't really know what normal operating temperature is for a transmission so I don't know if my setup is working correctly :biggrin: But it seems logical at this point.

Which brings me to something else, in that other post @TJBaker57 you posted a pic of all four TPMS sensors in ODB fusion. How did you do that? I definitely want to set up that screen in my app!
 

Blckshdw

Moderator
Nov 20, 2011
10,706
Tampa Bay Area, FL
I don't know of any other members who use that device. You may try your luck with some Youtube searching, maybe someone has posted a how-to. Much wider content pool, since it wouldn't be platform specific. :twocents:
 

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