yeah, the circuit is more evolved than say........a door light switch would
be.
to give you an idea ......
say you don't want your level sensor active.
Like you think things are getting confusing, and want to take that feature
out of the coolant gauge circuit, just temporarily, for troubleshooting
reasons.

if you unplug the sensor, the LED flashes continuously.
If you jumper the two wires together, same thing.
You need to jumper them with a resistor - that will keep the circuit in
either the temp gauge, or the control unit ( looks like a relay ) happy.
So it's an intelligent circuit, not a simple DC on/off circuit.

----- Original Message -----
From: "David Beierl" <dbeierl@ATTGLOBAL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, October 14, 2009 6:06 PM
Subject: Re: Coolant Low Level Light Useful?

> At 08:19 PM 10/14/2009, neil n wrote:
>>module, but giving it some more thought, it should be pretty simple to
>>wire in a 87/87a type relay from X on ignition switch. That way if the
>>ground opens (coolant low) the light should go on.
>
> Hi Neil -- that won't work.  Pmail me and we can talk about why.
>
> Yrs,
> d