Date:         Mon, 31 Aug 2009 22:27:56 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: the case of the curious blinking LED
Comments: To: Alan Felder <dieseldoofus@gmail.com>
In-Reply-To:  <3d35438b0908311911j9f6819k427da05f168b7cd7@mail.gmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 10:11 PM 8/31/2009, Alan Felder wrote:
>That's the first thing I thought about, the ignition
>switch.  Although, no other switch symptoms (yet).  I am wondering
>if a bad aux fan sensor would cause it to do this, or if I have it
>wired up incorrectly because it didn't do this before I

Nope.  The whole blinking (pun intended) circuit is inside the temp
gauge.  Whenever it sees power it's supposed to blink for three
seconds and then watch for an overheat input to the gauge.  When it
first sees one, the new type latches on and the old type blinks for
another three seconds and keeps looking.

The low-coolant part works by simulating an overheat.  The new
controller does it in short pulses, and the gauge itself doesn't move
appreciably.  The old one does it continuously, and the gauge pegs,
just as if there were steam coming out of every pore.

So the only things it ever sees are regulated panel power, panel
ground, and the temp input from the gauge sender.  It doesn't know
that the level controller is also lurking there waiting to give a
false alarm.  And the level controller will never send that signal
before a few seconds after the power goes on, because it takes that
long to figure out there's a problem with the level.

Them are the limits of what you have to work through.  It's not the
temp input connection to the panel, because a problem with that would
give a low reading, not high.  I suppose a wiring error is possible,
but I'd be surprised if it didn't peg the gauge and maybe burn it up.


  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"