Getting diagnostic data from serial cable

[Tom Cheesewright]

I would really like to be able to pull diagnostic information from the car into an onboard computer without having to plug an external device in or use software like INPA. Has anyone tried reading the output from the 20 pin connector into something like an Arduino using one of the serial adapters?

I can find lots of guides for doing it on OBD2 port but I don't think my 99 Z3 will conform to the relevant specs for that (though I'm going to test this with a Bluetooth OBD dongle now).

 

[NZ00Z3]

I have been involved with Z3's for over 6 years and have not seen anyone try and pull information using an Arduino. If you want to try it, read up on ADS adapters as you'll need one between the car and the serial port. ADS access works with true serial ports. It does not work with serial adapters or USB-serial leads. Tiny ADS https://openlabs.co/store/Tiny-ADS-Interface

There are several other ways of pulling information, depending on the information that you are after. The OBD11 port by the steering wheel only has engine (DME) information. If you want information from other modules, you need to use the 20 pin round port under the bonnet/hood.

The Scangauge is one device that has been used to display engine data. https://www.scangauge.com/products/scangauge-ii/

Others have used OBD11 adapters to connect through a blue tooth or WiFi wireless connection to the tablet/phone of their choice to display engine data.

I have used the TestO software through the 20 pin port to set up a temp logging system. http://www.bimmerforums.com/forum/showthread.php?1830510-Diagnostic-program-with-realtime-graph-view

I have heard of one Z3 owner who set up a surface pro in the boot/truck to auto turn on at power up and log data with TestO. He used it for performance testing and refining the tune in his DME. Can't find the tread to give you a link.

Hope this helps.

 

[Tom Cheesewright]

Thank you so much @Murray Wall - this is fantastically useful information and that board looks very usefully sized.

At the moment I have an old serial cable marked as EDIABAS OBDII with a 20-pin adapter on the end. I've tried hooking this into an Arduino (actually an ESP8266) with an RS-232 adapter to see if any data comes back when it is plugged into the car, but even though I've confirmed my code sketch is working, I get nothing. I'm guessing the diagnostic software has to send some sort of handshake before it starts receiving data.

May be that I need to get an old machine with a serial port running and capture the output from the other side to see what communication goes on between the two

BTW DME info won't be much use to me as I'm replacing the engine with an electric motor, so it's very much the other stuff that I need!

 

[Pingu]

My setup cost <£100.

It's an old XP laptop with serial port, 20 pin to RS232 cable, Testo and some Excel programming.

Testo shows data live, the gauges are excellent, but the graphs are not easy to read.

I download the data and build graphs in Excel.

https://zroadster.org/threads/testo-datalogger-what-do-you-think.18350/

 

[Tom Cheesewright]

Fascinating - thanks @Pingu. Now regretting cannibalising my last old laptop with a serial port for parts...

 

[handsomejackuk]

i just use a bluetooth obd reader plugged in to the 20 pin socket with a 20 pin to obd adaptor cable, then i run the torque app on my android mobile phone fitted to an adaptor in the car you can setup alerts monitor loads of different parameters, and live data view guages and graphs and read fault codes, i have an alert setup to monitor coolant temperature and alert me if it goes over a certain value, at least i know what coolant temperature is then and not from the dead weighted guage in the dash, can also monitor mpg range etc and its very accurate.

 

[Tom Cheesewright]

Will that work? I didn't think it would have sufficient compliance with the OBD standard for that but happy to give it a try!