Headlights -GM

Interesting piece of Trivia.

I had a front halogen bulb going dim on the
1990 Silhouette, which has a four bulb front system.
(two outers, low beam....two inners high beam).

Replaced the bulbs and started checking things out.

At low beam the two outer lamps come on
At high beam the two inner lamps come on (and the outer ones are off).

It's a two wire system... each switch handles V+ to a different set of lamps.

So, I checked three GM cars

1990 Olds Silhouette Mini-Van
1992 Chevy Lumina APV
2002 Chevy Monte Carlo LS


And, (believe it or not), on all cars, the low beam calls for
one set of two lamps. The high beam calls only for the other
set of two.

otoh my friends 1994 Buick Regal uses a four lamp system and when
using high beams all four lamps are lit !!!

Why would GM use two different headlight systems???

To convert this to a 4 light high beam system all I would
need to do it jumper hot from the high beams to the low beams using
a diode and quick connect coupler. Is this thinking correct ??

Thanks !!!

Perhaps the headlight capsule can't handle the excess heat, so only two
are then lit instead of four. Look at the 97 Grand Prix's, notorious
for the plastic headlight lens to literally fall off when driving.

A friend with a 92 Century drove for over a year with his high beams on
thinking that his low beam ( which was burned out for a year ) would
come on when the highbeams were on, but that wasn't the case.

The same Century had the LH turnsignal lens fall off the back part of
the housing. That was probably due to a poor adhesion not heat.

Only two lights on at a time here.

=========
Harryface
=========

1991 Pontiac Bonneville LE
3800 V6 ( C ), Black/Slate Grey
_~_~_~_~277, 300 miles_~_~_ ~_~_

"Harry Face" <harryface@webtv.net> wrote in message
news:11799-4049163E-203@storefull-3115.bay.webtv.net...
| Perhaps the headlight capsule can't handle the excess heat, so only two
| are then lit instead of four. Look at the 97 Grand Prix's, notorious
| for the plastic headlight lens to literally fall off when driving.
|
| A friend with a 92 Century drove for over a year with his high beams on
| thinking that his low beam ( which was burned out for a year ) would
| come on when the highbeams were on, but that wasn't the case.
|
| The same Century had the LH turnsignal lens fall off the back part of
| the housing. That was probably due to a poor adhesion not heat.
|
| Only two lights on at a time here.
|
| =========
| Harryface
| =========
|
| 1991 Pontiac Bonneville LE
| 3800 V6 ( C ), Black/Slate Grey
| _~_~_~_~277, 300 miles_~_~_ ~_~_
|
|

Quite possible. It could also be that they didn't design the reflective optics
to be used as a high-beam on the low-beam side on some models. In that case, a
user-designed conversion _may_ throw the wrong hi-beam pattern (illegal).

It's probably designed to do that. My 1990 Suburban works the same way
and that's the way it's supposed to work. They sell kits that will
allow all 4 lights to be on when High beams are selected but they're not
legal in all states.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
There are two classes of pedestrians in these days of reckless motor
traffic - the quick and the dead.
~ Lord Dewar 1933 ~

Climbing into a hot car is like buckling on a pistol. It is the great
equalizer. ~ Henry G. Felsen 1964 ~

Thanks all for responding..... I agree it designed
that way... thanks for pointing out the existance of
modification kits, I might do a conversion (if legal),
to obtain better close up illumination during hi-beam use.

Thanks again for responding....



On Fri, 05 Mar 2004 11:04:35 -0500, Peter <> wrote:

>Interesting piece of Trivia.
>
>I had a front halogen bulb going dim on the
>1990 Silhouette, which has a four bulb front system.
>(two outers, low beam....two inners high beam).
>
>Replaced the bulbs and started checking things out.
>
>At low beam the two outer lamps come on
>At high beam the two inner lamps come on (and the outer ones are off).
>
>It's a two wire system... each switch handles V+ to a different set of lamps.
>
>So, I checked three GM cars
>
>1990 Olds Silhouette Mini-Van
>1992 Chevy Lumina APV
>2002 Chevy Monte Carlo LS
>
>
>And, (believe it or not), on all cars, the low beam calls for
>one set of two lamps. The high beam calls only for the other
>set of two.
>
>otoh my friends 1994 Buick Regal uses a four lamp system and when
>using high beams all four lamps are lit !!!
>
>Why would GM use two different headlight systems???
>
>To convert this to a 4 light high beam system all I would
>need to do it jumper hot from the high beams to the low beams using
>a diode and quick connect coupler. Is this thinking correct ??
>
>Thanks !!!
>
>
>