Herbert,

 I'll look in my library at home tonight and see what I can find for you.
 I'll let you know later tonight if I can supply anything.

                                               Regards,

                                                 Jim



> Hello, thanks for the info. We've used this trick many times in the
> past and it has been very helpful, however we now need some more
> "internal" information to figure something out. First we need to know
> whether the car is coming out of closed loop, and if so what sensor is
> slightly out of spec causing closed loop to be lost. It's the kind of
> thing that doesn't cause a check engine light, since the car still
> works pretty much fine, it's just that our in-city mileage has gone up
> quite a bit, and if we don't figure it out we may need to get a new
> catalytic convertor before the next emission test. Thanks, TTYL
>
>> -----Original Message-----
>> From: James Paul [mailto:jamesp@intertex.net]
>> Sent: Tuesday, February 26, 2002 00:49
>> To: PICLIST@MITVMA.MIT.EDU
>> Cc: hgraf@EMAIL.COM
>> Subject: [EE]: Re: OBDI tools?
>>
>>
>>
>>  Herbert,
>>
>>  On GM cars, reading the codes is easy.   Under the dash usually close
>>  to the steering column is a connector with 12 or so positions in it.
>>  They are marked with letters.  Using a short piece of wire, connect
>>  terminal "S" to terminal "A".  Turn on the key, but do not start. The
>>  codes will flash out on the "Check Engine" or "Service Engine Soon"
>>  lamp in the instrument cluster.   As far as decoding what the codes
>>  mean, I could probably tell you later on today when I get home.
>>  Otherwise, you could go to the library and get a service manual for
>>  your vehicle or you possibly could talk to a mechanic and have him
>>  decode them for you. But anyway, that's how you can read the codes on
>>  GM vehicles.
>> If you have
>>  any other questions, let me know after about 6:00 PM tonight, and
>>  I'll see what I can dig up at home for you.
>>
>>  Hope this helps you out.
>>
>>
>>                                                   Regards,
>>
>>                                                     Jim
>>
>>
>> > Have an '87 Buick Park Avenue we'd like to diagnos a problem on. It
>> > would really be helpful if we had a "scan tool", however they are
>> > stupidly expensive. I've done some searches and it looks like the
>> > data that comes out of the ECM is simplly serial data at 8192bps at
>> > 12V voltage levels. Does anybody have more info on this? Is the
>> > output text or is it just a bunch of hex digits? If so anybody have
>> > a mapping for which hex digits mean what? For now I'll be using a PC
>> > laptop but it sounds like this might be something I can build with a
>> > PIC if I can find this info. Thanks for any help. TTYL
>> >
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>>
>
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