[Diy_efi] J1850 PWM Info Request

[Perry Harrington]

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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