

| Subject: | Re: the case of the curious blinking LED |
| From: | David Beierl |
| Date: | Mon, 31 Aug 2009 22:27:56 -0400 |
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"
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