Headlights modified from OEM configuration?

["Walter Coe" <Whalt@xxxx>]

Andrew & I have created a bit of confusion about the proper OEM
configuration of the DeLorean's headlight operation, so I'm posting an
explanation to the list to answer the following question asked by a list
member:

"Our DeLorean is also set up so all four headlights come on with the brights
selected. Are you sure that isn't a factory set up?"

Yes and no. You could very well have the factory setup and not realize what
is switching on and off. The low beams have two lights in one. In the same
headlight fixture there is a low beam and then a separate high beam assist.
When you switch on the high beams, the dedicated high beam fixtures turn on
(the ones closer to the fake grille) while the outer low beam fixtures
switch modes so that the low beam portion turns off and the high beam assist
portion turns on. So it may appear that all the filaments are powered when
really only the high beams and high beam assists are on. A modified car
would have ALL the filaments powered while the high beams are on.

The way to tell for sure on your car is to pull up to a wall with the
headlights on and flip on your high beams. Flipping the lever forward (away
from you) should latch the high beams & high beam assists on while switching
off the low beams. Pulling the lever toward you should switch the high
beams & high beam assists on but not interfere with the low beams -- meaning
that if the low beams are off, then they stay off. If they are already on,
then they stay on. But be aware that pulling the lever toward you is a
temporary 'flash' that should work even when the headlights are off.
Confusing eh? To further complicate matters, there is a wiring variation on
the brake lights so that some cars allow the brake lights to work while the
ignition is off while others only work while the ignition is on. I'm not
sure if this same variation also applies to the high beam 'flash' working
while the ignition & main headlight switch are off. Try yours to see.

If you want to simulate what it looks like to have your low beams modified
to stay on, then turn your headlights on and pull & hold the turn signal
lever toward the driver. This will power ALL the headlight filaments
simultaneously. If your lights are aimed at a close wall, then you should
see a total of six bright spots (three per side, two of which are coming
from each low beam fixture.)

There was a discussion about this on the DML last year (I think). Someone
was asking why the low beams shut off when the high beams turn on (that
might have been me(!), but I don't remember particulars like that). DMC Joe
spoke up and said that the reason for it is that having the area in front of
the car lit up causes the iris to constrict making it harder to see
distances at night. The DOT determined that people could see distances
better if the foreground was darker. So that is why the low beams don't run
with the high beams.

I have seen mail order catalogues (such as JC Whitney) that sell relay kits
that keep the low beams on with the high beams claiming that this is safer.
The ads read something to the effect of, "Why turn off your low beams when
you can have more light?" But the fact of the matter is that 'more' is not
always better.

Now the situation with the Xenarc HIDs is different. Those have to stay on
with the high beams because it takes a minute or so for them to warm up.
Switching them off while the high beams come on would be dangerous because
then you would have to wait for them to warm up each time while they come
back on. But keeping them on is not a disadvantage because the beam pattern
with it is tightly focused in a horizontal plane. They don't light the
immediate foreground as brightly as standard (American scatter style)
headlights. In comparison they are more like "short range high beams".
Then when you switch on the high beams with HIDs, they effectively extend
the range without using traditional high beam assists. In a sense, the high
beam fixtures ARE the high beam assists.

I hope this makes sense. :-)

Walt Tampa, FL