Date:         Fri, 19 Dec 2014 21:20:50 -0500
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Warning light
Comments: To: Dennis Jowell <dennisjowell@GMAIL.COM>
In-Reply-To:  <5C5F1C0C-E061-4EFC-8C12-E6D17D38A0CE@gmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 06:30 AM 11/6/2014, Dennis Jowell wrote:
>The buzzer/warning light goes off together and is located In the
>temperature gauge ( tachometer)
>Not by the oil can warning light speedometer area. It was going off
>at low idle coming off the interstate.
>I checked the coolant and it was low. Filled it yesterday now need
>to test drive. Snow coming in this morning so my test drive will be postponed.

Sounds like someone added a buzzer to the gauge blinker or
conceivably modified the oil pressure blink/buzz system.

In a stock 2.1l system. the oil light will blink any time it's
activated, but the LED itself does not self-blink; it's a normal
LED.  If you unplug the sender  by the water pump and rev above 2,000
rpm it will blink and a buzzer will sound.  The buzzer is on the
L-shaped circuit board located inside the speedometer, which parses
the two sender inputs and the tachometer signal and controls the
light and buzzer.

The temp gauge OTOH contains a self-blinking 5V LED that blinks any
time it has power.  It's driven by a ua741 op amp circuit that runs
for two seconds any time it's triggered and at power-up, and is
triggered any time the resistance to ground on the gauge sender line
falls to 35 ohms or below.  Its output pulls the negative lead of the
LED and the 5.1V zener diode in parallel with it negative from the
+10V supply rail of the gauge.  It's possible to take several mA at
five volts from this output, enough to drive a 5V/500 ohm reed relay,
with only slight effect on the brightness of the blinking LED.  Or a
transistor circuit could be devised in place of the reed relay.

If you can at some point document exactly what was done it could be
useful to others in the group.

Sorry for the delayed response; I accidentally sorted my mailbox
incorrectly and it put this in front of my eyes where I'd missed it before.

Yours,
David Beierl