Sunday 27 September 2020

getting OBDII to work on late 90s JDM toyota ECUs

 Some JDM toyota ecus are ISO14230-4(5 baud init) compliant

This protocol is poorly supported by most OBD2 android applications yet but some do support it well.

To make it worst not all BT obd2 dongles out there support this protocol either.

I was able to prove this configuration personally on 2 non obd1 JDM ECUs already

ST215 3S-GTE A/T (89661-21330)

ZZT231 2ZZ-GE M/T(89666-20060)

you might need to make an obd2 port in cases of an engine swap

In the celica case (zzt231) the north american equipped obd2 port was OK as found.the north american 2ZZ-GE used a different obd2 protocol but relied on the exact same wiring diagram so no work was needed.

first of all the obd2 port pinout must be like this.

SIL comes from the engine ECU matching pin. this will be case specific.

pin 4 and 5 are grounds (which may need to reach ECU grounds in case you get issues) 

B+ is 12v power for the tool connected on the obd2 port, I suggest not powering this at all time to avoid battery drain

an ELM327 BT dongle was used, it was a BAFX PRODUCTS OBDII Diagnostic interface. other elm327 dongles will work with varying level of success. if you already own some different models I suggest you try them out before buying the BAFX .

Car Gauge Lite

This app is definitely not my favorite but proved to work through out the tests!

first of all you need to pair your OBDII device in the android bluetooth settings dialog before starting the new app.

Here is the car gauge lite main screen.  

beware, this lite version is ridden with ads to a point that makes it extremely annoying and hard to conduct any serious work. A paid ad free version is available. I suggest you get the Lite version working before going for it.



In the application preferences you will need to check a very specific option for this to work at all.

after this,with the elm327 pluged into the car and key ON or engine running you will be able to bluetooth connect to it.


there will be 4 dialogs asking for selections to be made, keep in mind that my OBD2 bluetooth MAC address wont be the same as yours. you will have to look it up in the android bluetooth settings dialog and remember it.

At this point you are connected to the ECU !

like all modern OBDII android app you will have to spend endless time building your very personalized dashboard including the fields you care for.


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