Bench ecms

[peter paul fenske]

Dear Bruce

You have to look at ground analysis.
With no current draw from accessories engine starter ect
eng ground is ecm ground.
Turn something on and engine ground might measure -3volts
which is evil in ecm terms.

Also signal noise analysis.
An improper ground would let noise into the ecm.

Thus sensor ground shall always be used for sensors, O2 gnd fer
O2, and power ground for power ground, as well as injector returns
should go to back of engine block

Have a gun one.

:peter

At 07:29 PM 8/6/98 -0400, you 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.
>
>
>