How to send commands to ELM327 OBD interface

It looks like the device you buy is just a packaged version of the chip and a bit of glue electronics. Is the actual datasheet useful?

interface. I want to design a stand alone device that check long term fuel trim values along with some other parameters.

List of commands:

The real product page: (Note that v1.5 chips are all unlicensed clones).

Make your own ODB2 board:

Ideas and code: etc.... Google for "elm327 source code".

Great guys! ELM327 is a pre-programmed PIC processor. It communicates by RS-232, so probably I can set up another PIC through the USART and communicate with the ELM. And possibly use a 2x16 char LCD display to show the parameters. Brill !!!

probably I can set up another PIC through the USART and communicate with the ELM.

This forum and article might be of some help. "free OBD2 software with MPG calc"

Incidentally, I bought a Mini ELM327 BlueTooth on eBay to play with. The plan was to leave it plugged into my vehicle OBD2 connector and have it communicate performance numbers via BT to my Droid X phone while driving. The plan was ruined when I found myself with a dead car battery the next morning. It seems that the Mini ELM327 does not turn off when the ignition key is off, and continues to draw power. Actually, it drew enough power to get hot enough to partially melt the blue plastic case. A quick survey of other such devices indicates similar problems. I had to crack the case to install an on-off switch.

I wonder if it was defective? Maybe it latched up.

Otherwise, can you just hyperterminal to it and play around?

Nope. It still works. The eBay vendor was nice enough to sell me another one for essentially the cost of shipping as he was interested in the problem. The replacement did the same thing. Mine is similar to this one: There are several other form factors including one that's even smaller. I've tried two larger flavors, and they also don't turn off with the ignition key.

Probably you could. BlueGoof nicely emulates a serial COM port so any terminal emulator should work. However, it might be easier to just buy an RS-232 ELM327 device. I hope you enjoy typing AT commands. There are apps to make it easier:

Or the USB version to use with a laptop:

Actually, I need the Nissan/Infinti proprietary connector. Maybe a converter exists, but the damn SEO brings up catalytic converters when I do a search.

Found in a few seconds with Google searching for "OBD2 Nissan adapter".

Well close. The Infiniti socket is 16 pins and so is standard ODBII. But this is a 14 to 16 pin adapter.

And I thought only Apple uses GD proprietary connectors.

The shop manual calls the ODBII scanner the GST (general scanner tool), just to make the manual harder to read I suppose.

BTW, if you never did it, for like $20 or so, there are websites that let you download the official manuals. I suppose there are pirated manuals as well, but $20 seems fair considering what cars cost. You get a one day subscription to the service. it is really intended for repair shops.

probably I can set up another PIC through the USART and communicate with the ELM.

!!!

There is something weird about this, a PIC eating enough power to flatten a 12 V, 50 Ah or more battery in a few hours??? Hot enough to melt the case??? Where in hell is all that energy going?

???-)

probably I can set up another PIC through the USART and communicate with the ELM.

And someone with no knowledge that vehicles DO have "accessory" power that goes off when the ignition switch is off :-) ...Jim Thompson

probably I can set up another PIC through the USART and communicate with the ELM.

On the OBDII diagnostic port?

On Tue, 27 Nov 2012 00:41:42 -0800, josephkk wrote as underneath my scribble :

probably I can set up another PIC through the USART and communicate with the ELM.

I have had one of these clone ELM bluetooth units for about a year 1.5 version, no signs at all of overheating, gets slightly warm in use as you wd expect, I dont leave it plugged in doing nothing though....! Maybe OP has been unlucky in his units, but it seems to be a known problem, look on Amazon comments etc. C+

Bwahahahahah. Large companies have been using proprietary connectors since there were connectors, well over 100 years. How could you possibly be that naive?

so probably I can set up another PIC through the USART and communicate with the ELM.

Brill !!!

^^^^^

flatten

the

This is on the OBD2 connector, which does not depend on the ignition switch position. Please pay attention properly.

?-)

probably I can set up another PIC through the USART and communicate with the ELM.

It doesn't? When I get smog-checked, they plug into the OBD2, then turn the key!!! ...Jim Thompson

It's just bad designs/programmers. Poorly design products can kill any battery. Don't they know about low-power/idle/standby modes? Perhaps they do and will be ready to sell you an upgrade with a premium price.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

The 12 volts on the ODB2 connector is directly to the battery. It is on all the time.