-----Original Message-----
From: David Beierl [mailto:dbeierl@attglobal.net]
Sent: Tuesday, July 11, 2000 10:28 AM
To: vanagon@gerry.vanagon.com
Subject: Re: Help!

At 14:00 7/8/2000, bpchristensen1@home.com wrote:
>Headlight problem; low beams work fine, but when I switch to high beams,
the
>high beam won't light on the driver's side, and the primary filament in the
>main lamp goes out.

By primary I assume you mean the low-beam filament.  It's actually
*supposed* to go out when you put the high-beams on.   Low beam is driven
by 56b (through fuse s21 for left side and s22 for right).  High beam is
56a, s10 and s9.  The dimmer switch simply switches the 56 lead from the
light switch (which gets its power from the load reduction relay, X
terminal on the light switch) to either of 56a or 56b.  So:

1) bad ground from that headlight assembly.  The low beam still works
because it's grounding through the high-beam filaments, just like the guy
ahead of you whose running light goes out every time he puts the brakes
on.  His running light is grounding through the stop lamp filament, but the
ground goes away (and neither light works) when the stop lamp is energized.

2) bad s10

3) bad internal panel wiring, fuse s10 to terminal c17.

4) bad 56a wire from panel to light assembly.

My bet is on number one, but you can check by testing for 12v at the
separate high-beam lamp (highs switched on, duh...).  If you have 12v
there, it's a bad ground.  If not, start following the other stuff back
until you find 12v.  It's not the switch, since the other side works
ok.  If you have voltage on one end of something and not on the other end,
that's the busted part.

>I notice that in the wiring diagram that each lamp has two circuits - 56a
>and 56b, and both sides tie together somewhere behind the dash.

High and low beams.

>I checked for continuity in both circuits from the dimmer switch (and the
>dimmer switch itself) and everything seems good. One weird (?) thing I
>noticed was that the "hot" side of the 56a circuit had continuity to
ground.
>Is this just due to the bulb?  (i.e. not abnormal).

Hot resistance of a 65-watt headlight bulb is about one fifth of an
ohm.  Cold resistance much less...normal.

>Any suggestions?  All I can think of is a short in the wiring between the
>driver's side lamp and the dimmer switch, which I imagine will be a
>nightmare to troubleshoot.

That's not it...an open maybe, but no short.  And no problem to find if you
need to. :)

cheers
d

David Beierl - dbeierl@attglobal.net <<- New address becomes mandatory on 1
Oct, optional until then.