[Diy_efi] Re: J1850 PWM Info Request

Rick Richard saba_apollo at hotmail.com
Mon Feb 10 23:01:34 GMT 2003


This is the very part that I want to make my own open-source version of.
The ELM is a good product and it is priced reasonably, but I would rather 
program a PIC myself than purchase a preprogrammed PIC.  It would save a 
couple dollars and I could change the interface if I needed to.


From: Gerhard Mueller <gerhard at tricom.han.de>
>Reply-To: gerhard at tricom.han.de, List for general do-it-yourself EFI 
>talk<diy_efi at diy-efi.org>
>To: diy_efi at diy-efi.org
>Subject: [Diy_efi] Re: J1850 PWM Info Request
>Date: Mon, 10 Feb 2003 16:42:04 +0200
>
>Hello Rick Richard
>
>you may want to get the ELM320 PIC from ElmElectronics.
>
>Gerhard
>
>Am 10-Feb-03 schrieb Rick Richard:
> > I don't understand what the deal is.  I asked, I did not demand.
> > I thought the purpose of a mailing list like this was to share 
>information
> > and resources.  Perhaps you think it is presumptious of me to assume 
>that
> > someone here has this information?  I don't think so, because I've read
> > archives of this list where people mention owning the SAE book with the
> > protocol information in it.
> >
> > I don't understand the relevance of "having a real job." If you have the
> > book, but don't have the time to share the info from it, then I 
>understand.
> > If someone has this info and is willing to share it, however, I'd rather 
>do
> > it that way than needlessly spend $80+ on a book that I would rather not
> > buy.
> >
> > All I want to do is make an open source PIC program to convert the J1850 
>PWM
> > to a serial interface for use with one of the many scantool software
> > packages out there. VPW Is very well documented but few people seem to 
>care
> > about the ford PWM and the DIY kits that are out there for it are
> > closed-source.
> >
> >
> >
> >> From: Mike <erazmus at iinet.net.au>
> >> Reply-To: List for general do-it-yourself EFI talk 
><diy_efi at diy-efi.org>
> >> To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
> >> Subject: Re: [Diy_efi] J1850 PWM Info Request
> >> Date: Mon, 10 Feb 2003 12:49:45
> >>
> >> Presumptive, or mildy impertinent I would have thought ;-)
> >>
> >> We aint a free library service, some of us have real jobs where
> >> people pay $200 an hour (on those rare occasions :)
> >>
> >> rgds
> >>
> >> mike
> >>
> >>
> >> At 08:42 PM 9/2/2003 -0800, you wrote:
> >>> Rick,
> >>>
> >>> Your approach at asking for information is a *little* coarse.  I don't
> >> have
> >>> any of the SAE books, but I can recommend a good book that has all of 
>the
> >>> Ford diag codes listed and a little bit of info.
> >>>
> >>> My suggestions are these:
> >>>
> >>> Get "Ford Tuning" by Ivan J. Kotzig.  He's the founder of Diablosport.
> >> The
> >>> book is a little lite on tech stuff, but it does have little bits of
> >> jewels.
> >>> On page 108 they describe some of the logical protocol used for the 
>PWM.
> >> They
> >>> also describe the PWM encoding itself.  This is a good starting point 
>and
> >>> reference.
> >>>
> >>> My next suggestion is to by an AutoXray and tap into the Data+ line 
>for
> >> the PWM.
> >>> Use a logic analyzer or a circuit of your own design to sniff the data
> >> off
> >>> the bus.  You should be able to get a fairly complete working example
> >> using
> >>> this method.
> >>>
> >>> The rest is up to you.  There is a Yahoo group for an open OBDII comm
> >> interface,
> >>> but it implements the SAE proto and not the PWM.
> >>>
> >>> --Perry
> >>>
> >>> On Sun, Feb 09, 2003 at 07:42:58PM -0800, Rick Richard wrote:
> >>>> I know someone on this list as either the SAE J1850 standard or the 
>SAE
> >>>> HS-3000 book.  I'd like to implement the J1850 PWM protocol that Ford
> >> uses,
> >>>> but I can't find the protocol specs online, the books are expensive,
> >> and
> >> the
> >>>> custom chips are closed-source.
> >>>>
> >>>> Would someone scan the info out of their book(s) and email them to 
>me?
> >>>> It would be greatly appreciated!
> >>>> -Rick
> >>>
> >>> --
> >>> Perry Harrington            Data Acquisition & Instrumentation, Inc
> >>> perry at dainst dot com                     http://www.dainst.com/
> >>>
> >>> Those who would give up essential liberty to purchase a little 
>temporary
> >> safety
> >>> deserve neither liberty or safety. Nor, are they likely to end up with
> >> either.
> >>>                             -- Benjamin Franklin
> >>>
> >>> _______________________________________________
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> >>> Diy_efi at diy-efi.org
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> >>>
> >>>
> >>
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