Hi all - long time no speak. Hope everyone had a good Xmas and new year :-)

Anyway, to the problem:

I have a friend who has a Renault Scenic 2004 model, and it's misbehaving
rather badly. On operation of certain controls (e.g. indicators, lights,
etc) the dashboard displays go crazy and occasionally the car completely
shuts down until the battery is disconnected and reconnected.
I had a quick look today and my guess is it's probably a bad contact on the
battery positive or earth (I wiggled the positive terminal lead and got the
fault to come and go. So we took all the contacts off and I have cleaned
them up ready for refitting everything tomorrow. Hopefully this and a check
of the earth points will be all that is needed...

BUT

In case the above doesn't solve things, and out of the desire to both help
out and expand my electronic knowledge into automotive protocol territory,
I thought about hacking into the ODB-II bus and checking for error codes.
>From a quick Google, what I understand, it being a european car (we're in
the UK) the EODB standard is ISO9141-2 (according to the WIki page -
http://en.wikipedia.org/wiki/On-board_diagnostics#EOBD)
Or I have just discovered it maybe a similar protocol in the Scenic - ISO
14230-4 KWP. It may even be CAN if it's one of the models made that year,
but I'm assuming it's the former type for now.

It seems the protocol is like UART but one line bi-directional, with speeds
of 10.4kbps IIRC. So I (think I) have a good idea where to start (i.e. bit
banging with a PIC18 or 24 and using some simple transistor level
translators or a MAX232) but if anyone has experience in this area, advice
or even some ready written routines (note - just found some useful stuff
here: http://picobdii.googlecode.com/svn/trunk/Code/), a decent schematic
(some of the ones I found on the 'net were terrible) or any useful
info/datasheets on the protocol to speed things up it would be most
appreciated.
Ideally I'd like to hack something together immediately and try it out as
soon as possible, as my friend is pretty stuck without his car and doesn't
really have the funds/inclination to take it to a Renault dealer (also past
experience with the local one suggests they will be pretty useless and
expensive)

Thanks for reading,
Oli

--=20



Oli Glaser

Technical Development

Irwell Springs Ltd

oli.glaser@irwellsprings.com



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