Re: Headlamp Swaps

[Greg Amy <grega@pobox.com>]

From: "Lewis, Gary M" <Gary.Lewis@West.Boeing.com>

>>>Per another Q-Lister's advice (see below), I've decided to upgrade my
lights using harness and bulb upgrades.  The Mfg'r of the harness I'm
looking at says I can go from 45w/65w (pathetic) to 80w/100w.  About $80.
Sound good.  One catch... the computer idiot light for a burned out
headlight will turn on.  How can I turn this indicator off?

Gary, you can't. I just did this upgrade last weekend on my 1991 200Q. I
like the results, but I found it to be a pain in the ass to have that
indicator light come on.

Now, on the 1991 200, you can push the little button to make it go away.
However, EVERY time you select high beams then go back to low beams, it
beeps at you and lights the indicator again! What a pain!

I pored over the Bentley, and found that this car's system watches only the
low beam system for faults, and will only report if a low-end filament is
out. I rang out the relay/wiring harness (mine is from Competition Limited)
and compared it to the Bentley diagrams.

Here's the scoop. If you were to switch to the 55/100W lamps, you can run
your low beams off the factory wiring harness. Then, you'll have 100W for
high beam. Frankly, that's all I need; when I'm on low beam here in CT it's
usually on the lighted highways.

To make this modification, find the relay that has the two yellow wires
going to it from the center contact of each bulb on the new harness; this is
the low-beam positive wire. From the new harness, cut the yellow wire about
1 foot from each of the new harnesses headlamp plug, and Scotch-Lok it to
the center (yellow) wire on the car's headlamp plug. Remove the relay that
controls the low beams; it's no longer needed.

What you've just done is run the positive low beam wire from the car to the
positive low beam wire to the new harness. Then, you're using the new
harness and relays to run the 100W high beams. This way, you get 100W
straight off the alternator for the high beams, and 55W for low. The car's
electrical system still sees the load on the low side, and the "bulb-out"
indicator goes away.

As an aside, I ran the harnesses positive wires to underneath the positive
terminal that's on top the washer bottle. Certainly nice of them to graft on
a ring terminal that fits there perfectly! It was a 30-minute job, max.

Of course, if you haven't ordered the kit yet, Competition Limited offers to
do all this for you for an additional $10, and it comes with 55/100W bulbs.
I found this out too late, so I had to order another set of bulbs.

Which means, of course, that I have a new pair of 85/100 9004 bulbs to
anyone willing to buy them. Cheap.

Greg Amy
Milford, CT
1991 200Q