Tachometer input signal.

[btpeet at effervescent.com (Bradley Peet)]

I don't know if you're familiar with transistors, but the ECU outputs are
open-collector switches that sink current to ground.  +12V is supplied to
one side of the coil at all times, the other end of the coil goes to ECU (or
an ignition amplifier) that switches it to ground.

I'd have to assume that the tachometer has it's own 12V source and needs the
"input" pulled to ground, as is done with the coil.  I'm going to head out
to the garage now and perform a few tests to try and verify that theory.

Bradley

> -----Original Message-----
> From: Marc Scirocco Qu?bec [mailto:marc_scirocco@sympatico.ca]
> Sent: Saturday, May 24, 2003 1:51 PM
> To: 'Bradley Peet'; 'Scirocco List'
> Subject: RE: Tachometer input signal.
>
>
> Looking at your diagram, what is input, and what is output?
> Because it looks
> as the ECU outputs are facing the wrong end of the diodes. What is the
> intended signal flow? From the ECU to the tach? If yes, perhaps you had
> better reverse the diodes.
>
> Cheers.
>
> Marc
> '83 Scirocco
> '88 Scirocco Slegato
>
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