Date:         Wed, 17 Nov 1999 15:28:42 -0500
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: What to do for a dim dashboard light?
Comments: To: "Alan J. Flint" <ajflint@ITSA.UCSF.EDU>
In-Reply-To:  <Pine.A41.4.20.9911170606230.16938-100000@itsa.ucsf.edu>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 09:10 11/17/99 , Alan J. Flint wrote:
>Listers:
>         I have a very dim "High beam" indicator light.  I can't see if my
>high beams are on until its really dark outside (what's the fun in
>that).  I was planning to replace the bulb, but I wonder from some recent
>posts if cleaning contacts at the headlight switch or elsewhere would be a
>better initial step.

High beam indicator is an incandescent bulb with a blue lens over it that
looks like the end of a T-1 3/4 LED.  It is fed directly from the high-beam
supply voltage for one headlamp, and has a series resistor btw the
indicator bulb and ground.   On the '84 panel I'm looking at the resistor
is 100 ohms, and the cold resistance of the bulb is 9.7 ohms.  Hot
resistance much higher, of course.  At 13.6 volts supply voltage, the bulb
lights with a cheerful pale yellow -- whiter than a kerosene lantern
flame.  I find it (in the panel) easily visible in dim daylight, and with
difficulty in bright daylight.

Incandescent bulbs do get dimmer with age (because the tungsten of the
filament gets plated onto the inside of the bulb) but I seriously doubt
that is your problem.  The bulb from this panel with about 180k miles on it
is still clear (well, it's a frosted bulb...).  There is no other mechanism
for such a bulb to become dimmer in use.  Look for bad contact somewhere or
for the resistor to have changed value.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"