euro lights/ecodes

Djdawson2 at Djdawson2 at
Wed May 29 14:18:41 EDT 2002

[ Picked text/plain from multipart/alternative ]
OK, I'm not looking for trouble here but... SJ says:

The relays will be 'very' exposed to the elements, there is no real way to
avoid this, the slightest gap between the connector/s and the relay start
corroding (high temp fluctuation and humidity are incongruous).  I also
routinely measure higher resistance thru the 30/15 circuit when the relay is
activated on "outside installs', which means that the "points" type wear
increases when exposed to the elements.

Dave politely asks:

Isn't a great deal of this car's wiring (and relays) an "outside install"...
my fuse box is under the hood, and it contains a handful of relays.  Was this
a mistake on Audi's part, or could we achieve similar good results by
installing well protected relays for our headlights in the engine compartment?

SJ politely comments:

WRT using the Alternator/Starter/Jumper post...  Any halogen bulb
manufacturer will tell you that bulb life is GREATLY affected by voltage.
Putting a tap from a line that feeds from the starter circuit couldn't put a
higher fluctuation into the supply voltage equation.

Dave respectfully inquires:

How does the starter provide such a current fluctuation?  I'm not in the
habit of starting my car with the headlights on, but even if I did, that
circuit goes dead upon starter activation... on any German car I've ever
owned.  Hit the starter, lights go off, release and they're back on.  This,
to me, would appear no more harmful than turning them on and off.

SJ observantly states:

If you gander at the offroad boards (where halogens hang like landing
lights), warnings abound regarding using the alternator line as the supply
voltage.  The battery is your best capacitor wrt voltage flucutations, use

Dave replies (politely, and with all due respect):

We're not talking about using the alternator line here.  We're talking about
using a very heavy gauge feed.  I'm hoping that you're not suggesting that
the jump post is somehow not directly connected to the battery, and taking
advantage of its capacity (yes, via a post on the starter... but we just
eliminated that as a possible source for current fluctuation).  I'm
suggesting that you already have a direct run from the battery to the jump
post that consists of 2 sections of wire connected together on the starter
post.  I'm also certain of the fact that the headlight circuit is deactivated
during starter use, which eliminates the starter as a factor here... assuming
that you use the original headlight wiring as the means to trip your euro
light relays.  With these 2 things in mind, the only issue that remains is
relay life/performance.  I believe it is possible to protect the relays
adequately within the engine compartment.  What else is really left?

Wiring runs... I believe you could accomplish the "post" type of install
using 1/3 of the wire length required to go the other route.  In a low
voltage/high current application, there are benefits to keeping those runs as
short as possible.

That's really all I've got to say... I'd sum it up with "to each his own".
Believe me, Scott, I'm aware of the fact that you knew more about Audi's 10
years ago than I'll know in 2020... and I respect your opinions and
knowledge.  I believe your method is very sound, and may quite possibly
outlast a quality underhood install.  But, I would have a hard time
justifying running a high capacity line from the battery forward when one
already exists.  And I'd personally have a hard time justifying the time and
effort required to keep $8 relays inside my car.
No more comments from me about euro light installs... again, this stuff is
just my opinion... and not implied to be any better than Scott's.  I believe
both methods can achieve great results.


More information about the 200q20v mailing list