Re: No "High flash"

[rdh@sli.com (Robert D. Houk)]

   Howdy, group.  Question de jour:  I discovered last night that my 
   1990 200T no longer will execute the handy "high beam flick" when 
   ...
   a)  Has this happened to anyone else?  If so, any war stories?
   b)  Is there a (possibly defective) relay which causes this "flick" 
   to occur? (Of course, I KNOW the solution won't be that simple.)
   c)  Any way that my running 100W highs/60W low halogen bulba might 
   have contributed to this??

Sounds like my flick-to-wipe wiper control.

In my '83 UrQ, the wiper (and headlight) "switch contacts" are open and
exposed to the air and get dirty/corroded fairly easily and regularly.
Every 4 to 6 months I have to "clean" the switch contacts and my wipers
(and washer) start working reliably again.

Cleaning is really trivial (especially the flick-to-wipe contacts, which
are just under the lever, and exposed if the bottom steering column cover
is, um, missing). There is a special $0.89 part (which for the life of me
I cannot remember the name of, again) available at most EE/techie stores
which is basically a "tiny flexible file" with a grit approaching that of
crocus cloth (very VERY fine - you can't really feel it as grit, just a
kinda of grippy surface that wears down your fingernail if you slide it
along far enough) or jeweler's rouge. It is expressly for cleaning "Relay
Contacts" and switch contacts and the like. Stick it inbetween the two
contact "buttons", pull the switch closed, pull the "file" out. Repeat
several times, and *poof* clean contacts. Be careful to pull the "file"
out straight and perpendicular to contacts... (you want to keep the two
contact surfaces flat and polished where they meet each other)

In addition to "dirty and corroded", contacts normally "pit" with age.
This pitting is directly (zero'th order approximation) proportional to
the amount of power being switched (i.e., the size of the electrical arcs
when the contacts open and close), determining how much contact surface is
vaporized/redeposited-elsewhere. Running 100W highs probably increases the
current load almost double the "stock" load. From my experience, Audi un-
derdesigns their electricals anyways, so you are overloading a probably-
already overloaded switch contact, and pitting the bejezus out of it. You
will probably have to replace the switch, but might well be able to sal-
vage it with careful "filing" of the contact buttons (if they're exposed
and reachable).

You can "experiment" with "sandpaper" (or emory boards), but they are 
way way to rough for a proper surface finish on the switch contacts. In
a pinch, it may make the switch work briefly, but the rough surface fin-
ish will just exacerbate future pitting... (and sandpaper/crocus-cloth/
etc will also "round" the edges of the contact buttons, resulting in re-
duced contact patch...).

For high-power lights, you gotta go the relays route, leaving the switch
contacts' only load to switch the relays (on my UrQ, the low beams are
more-or-less left stock [more less than more, I've completely bypassed
the resistor (er, fuse) box and ignition switch with my own 10ga dedi-
cated (and independently fused!) wiring *up to the light switch*, which
brings me from 9.6v stock to nearly 13v measured at the lamp terminals],
and the high beams are relay-switched although through stock wiring
still (easier, and it only costs me maybe half-a-volt max) after the
relays to the bulbs.

If only we could get Audi to hire *one* bright high school kid . . .

					-RDH