Date:         Thu, 21 Jun 2012 20:53:42 -0400
Reply-To:     Mike S <mikes@FLATSURFACE.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mike S <mikes@FLATSURFACE.COM>
Subject:      Re: CO Adjusting Screw. PO Set it All The Way In? Base Setting?
Comments: To: neil n <musomuso@GMAIL.COM>
In-Reply-To:  <CAB2RwfieUSzcXbpTu4F1n2RFGa5EJVXYVd6F-h-tSG3x5sHXnQ@mail.gmail.com>
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On 6/21/2012 8:27 PM, neil n wrote:

> Would shunting in an LED in parallel complete the circuit so ECU thinks the
> throttle valve switch was closed 100% of the time?

Probably not. The ECU was designed to expect the voltage to go very
close to 0 when the switch closes. There's probably a simple bipolar
transistor input to sense that, which would toggle at about 0.7 V (the
typical threshold for a silicon junction). A red LED has a typical
forward voltage drop of around 2.1 V (other colors usually higher). It
won't pull any current unless the voltage is higher than that, so it
wouldn't pull the signal down enough to signal the ECU.