attn: ECU OBD Hackers - emulate the select monitor using windows and RS232

[rmjjensen]

I want to get some information out of the ECU on the fly. I figure I have a computer in the car already so I'm more than half way there. I know standard OBDI / II cars communicate through serial data, and I'm going to go ahead and assume that the select monitor does the same.

So far I've accumulated the following information regarding a 92 Subaru SVX:

There's 3 access ports coming off of the ECU as follows:

The Diagnosis Connector
..Black w/ Blue - Ground
..Blue w/ White - Read Memory Connector
..Orange - Test Mode Connector

The Check Connector
..Orange - Test Mode Connector
..Brown w/ White - Select Monitor (Tx)
..Light Green w/ Red - Select Monitor (Rx)

Select Monitor Connector
..Brown w/ Red - +12V Ign
..Brown w/ White - Select Monitor (Tx)
..Light Green w/ Red - Select Monitor (Rx)
..Blue w/ Yellow - Trouble Code Output
..Black w/ Red - Ground

So I'm planning on using this IC: http://www.elmelectronics.com/DSheets/ELM323DS.pdf to communicate with the select monitor and the RS232 port on the car computer. I'm guessing if I just use the select monitor Tx and Rx lines this should work perfectly fine.

Does anything know if there's anything special regarding the select monitor? Hopefully this goes nice and smooth. Do I even need the ELM IC chip? I need to know if the select monitor uses the ISO9141 or ISO14230 protocols

[SVXtasy]

This is an excellent idea! i would love to do it. PM me if you get it working i will do soem looking around and see if i can find any info on it.

[drivemusicnow]

The one problem that usually comes into play is that the ECU doesn't have an easily defined "language". This may not be the case with the SVX, however with DSMs, its taken quite a bit of "hacking" to figure out which sections of code do what. if it follows one of the protocols though, that would be awesome.

[rmjjensen]

Originally Posted by drivemusicnow

The one problem that usually comes into play is that the ECU doesn't have an easily defined "language". This may not be the case with the SVX, however with DSMs, its taken quite a bit of "hacking" to figure out which sections of code do what. if it follows one of the protocols though, that would be awesome.

Yes that's my main concern. Elm makes three chips that communicate with generic obd protocols. The link I posted is the most generic chip to communicate with an obd system ....but as for the select monitor - I have no clue