[Diy_efi] OBD2 emulation

[Steve Ravet]

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Bobby Yates Emory
> Sent: Tuesday, April 03, 2007 1:13 AM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] OBD2 emulation
> 
> Steve,
> 
> I don't think he wanted to be able to run the OBD 2 test.  I 
> think he just wanted to put the correct signals to the OBD 2 
> connector so the OBD 2 scan tool reports that there are no 
> codes stored.
> 
> That should be simpler, but your freescale idea may be a good 
> way to do it.

It's not as simple as reporting no codes stored.  The tester has a
procedure that it goes through and it expects the car to respond
appropriately at each step.  This includes commanding the CEL to come
on, and the operator must verify that it actually comes on.  There were
initially some cars (Mercedes and Mitsubishi) that did not respond
appropriately to the various queries that the tester made and were
flunked although they were brand new.  In some cases dealers were forced
to buy back perfectly good cars because they could not be inspected.

The way to do this is to get a copy of that flowchart and implement it
in firmware in a microcontroller that includes an OBD2 interface.  If I
can dig up the one I saw before I'll post it on the twiki.

--steve


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