Hi Oli, Search for ELM327, from ELMElectronics, the data sheets will give you a good insigth into what is involved. The ELM327 is actually a PIC with there own firmware. There is masses of info on net and several websites that will have the fault codes for you car. Good luck. Best Regards Luis On 8 Feb 2013 02:09, "Oli Glaser" wrote: > 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 t= he > battery positive or earth (I wiggled the positive terminal lead and got t= he > 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 che= ck > 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 hel= p > 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 i= n > 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 spee= ds > of 10.4kbps IIRC. So I (think I) have a good idea where to start (i.e. bi= t > banging with a PIC18 or 24 and using some simple transistor level > translators or a MAX232) but if anyone has experience in this area, advic= e > 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 pa= st > experience with the local one suggests they will be pretty useless and > expensive) > > Thanks for reading, > Oli > > -- > > > > Oli Glaser > > Technical Development > > Irwell Springs Ltd > > oli.glaser@irwellsprings.com > > > > This email and any attachments to it may be confidential and are intended > solely for the use of the individual to whom it is addressed. Any views o= r > opinions expressed are solely those of the author and do not necessarily > represent those of Irwell Springs Ltd. If you are not the intended > recipient of this email, you must neither take any action based upon its > contents, nor copy or show it to anyone. Please contact the sender if yo= u > believe you have received this email in error. > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .