Schroedinger

Anyone here using an OBD2 monitor plugin with a phone app? I did a forum search, and all I could find was a thread from 2012. Figured I would start a new one.

I wanted to monitor the transmission temperature of my 2015 Toyota Sienna van while I was towing, so I bought one of these...


to use with my Iphone 10 and the OBD Fusion app. I'm completely amazed at how well this thing works and how much information is available. The app developers dug deep to configure hundreds of PID's for different makes of vehicle, pretty much every sensor and process in the vehicle can be monitored.

Turns out that the trans temp was not one of the pre-configured PID's. With a little Google-Fu, I found the following parameters to make a custom PID for trans temp:

module/header: 7E1
OBD mode: 21
PID #: 82
equation: ((A*256+B)*(84/1000)-480)/12

It works like a champ, despite my complete lack of knowledge of what any of that **** is. So my questions:

- what "language" is this that the device recognizes?
- are there any easy references available to get up the learning curve?
- what other functions have you found useful with these tools?

I feel like there's greatness here, but right now I'm like a monkey poking a spacecraft with a stick.

gooflophaze

https://en.wikipedia.org/wiki/OBD-II_PIDs

I use the cheapy ELM327 knockoff devices - $4 shipped of ebay. They work pretty well with canbus, don't work at all with some of the earlier protocols - but realtime information (mode 1) was never a real strong suite of the earlier protocols because of their slow speed (typically 10kbps - canbus, mandated as the protocol to standardize on in 2008, runs at 500kbps). Mode 22 (and 21 - extended data) PIDs are usually published by the SAE and/or manufacturers for a licensing fee (10k a year) for scanner makers (snap on etc) but often make it out through the usual means.

As far as language.. what do you want to know? I do some hunting in the raw streams with the use of a rpi and a dual mcp2515-based board of my own design with a little python to stitch things together.

Schroedinger

Thank you. I understand about 10% of what you wrote, but the Wiki has a bunch of good information to get me pointed in the right direction.