Bench ecms

[Bruce Plecan]

-----Original Message-----
From: mrvette <mrvette at bellsouth.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Friday, August 07, 1998 9:12 AM
Subject: Re: Bench ecms


>I am assuming you are a EE candidate at a minimun

Nope, total EE education is radio shack, and reading Forret Mimms.
As of late reading some other stuff.

, so I shouldn't have to say
>anything more than that the engine block is the ground for all sensors,
Not the
>body of the car....your starting sequence and the crazy currents through
the
>battery circuit and etc. could/would drive the computer crazy....and the
use of
>several grounds/+5volt wires is for the obvious ground/feed loop problems,
if
>you consider the various possibilities of inductive feedback from other
>hi-current wires...you can get my drift.....at any rate, wire it like it
says in
>the wiring diagrams from your local GM dealer's copy machine....they been
very
>good to me, when asked nicely.....GENE

>From your post the other day, (I think it was you), I thought you were
saying just divide them up, and tie them to the intake.  I've been a
follower of how the manual says to do it.
Cheers
Bruce
>
>Bruce Plecan wrote:
>>
>> I had been told the sensor grounds on a gm ecm floated in reference to
the
>> chassis ground, well that doesn't appear to be correct, everything is
just a
>> couple tenths of an ohm from true ground.
>> With no displayed voltage drops across grounds.
>> While still seperated, does it really matter if sensor grounds go to
>> chassis, on an actual car?.    If so then where Have I strayed to having
>> had sensor ground problems????....
>>
>> For coolant temp, and intake air temps, I was just going to share
>> resistances.  Tieing grounds together.
>>
>> For TPS, and MAP I was going to tie the grounds together, use the
>> +5 from one ecm, and then share the sensor's output.
>> YES/NO??????..
>>
>> Cheers
>> Bruce        RPM signals applied to both ecms, and powered up
>>                   leds flashed and no problems today.
>>                   The cat has grown boarded with the flashing LEDs,
>>                   but the staff is acting like their inna stupor.
>
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