Blau headlight harness failure

[Marc Swanson]

> > Anybody else have a problem like this?
>
> Not like it, but related to headlights and wiring and
> Blau...  When I replaced my burned out headlight a few
> weeks ago, there was some slight charring around the
> connector to the bulb.  I, too, did not fault the Blau
> harness I have as I was running 80/100W bulbs.


hmm, that should be just fine.  I've been running 80/100 H4's and 130W
H1's for years in both my cars.  This is the first non-bulb failure I've
had and it certainly wasn't due to overloading of the harness....  Or
was it?

total high beam power consumption: (100+130)*2 = 460 watts
P=VI, I=P/V
I = 460W/13V (around there with the car running) =  35 Amps.


Hmmm.... When I opened up the wiring harness I realized that on my 90
I've only been using 2 of the 3 relays all this time..  The 90 harness
that I bought came with a set of connectors for those lights that use a
separate harness for the H1 connector (one of those molex style two pin
deals).  On my 90, there is only one 4 pin round connector
(low,high,park,ground) on the back of the lights that leads to an
internal wiring harness inside the headlight that then connects to the
H4 and H1 bulbs. I didn't think much of it when I installed the harness
since I specifically told them what kind of lights I had and the
instructions just say not to connect the other harness if your lights
don't use them.

This is really pushing the limit of the wiring since there is a single
12 gauge wire feeding each relay block and the high beams are drawing 35
amps through one relay.  While the relay is rated to take it (40 amps),
you are only supposed to draw 20 amps from stranded 12 gauge wire.  I
wonder if this sped along the demise of that connection point?

Naturally when I found this out over the weekend I 'fixed' the harness
by routing one headlight high beam circuit through the previously unused
third relay and the other through the existing relay.  This way, at any
given time I'm 'only' pulling ~18 amps through any single 12 gauge wire
which puts me within spec.


I think maybe I oughta call Blau.  I wonder if they sell this same
harness configuration to others with my setup?  If my math is right,
they shouldn't...

Later

--
-Marc
87' 4ktq
88' 90q
www.mswanson.com/audi