The Stovebolt Site Forums The Shop Area The Electrical Bay Headlight hi-beams

I have a basic headlight question. When I switch from low-beam to hi-beam, does the low-beam turn off when the hi-beam comes on or are both on? I am re-wiring from scratch. It seems simple but then I started over thinking it.

Low beam is off when the high beam is on.

It's an either/or situation that can be confirmed with a test light or a voltmeter at the dimmer switch. That's why there are two filament connectors and one ground pin on a sealed beam bulb.
Jerry

What about 4 headlight sealed beam systems? Both high and low beam lamps illuminate when high beam switch is activated.

Why the difference between 4 lamp and 2 lamp sealed beam systems?

I think it's the same way with 4 headlight systems. I just looked up a '59 car wiring diagram (has the 4 headlight system) and they're separate circuits from the dimmer switch, and I doubt that the dimmer switch is any different than the 2 headlight system. Per the GMPartswiki, the dimmer switch was the same from 55.2 thru 60 for Chev & GMC trucks.

The switch is the same and the wiring is probably the same but when the high beams are turned on in a quad lamp system, all four headlamps are on.

Why would a dual headlamp system work differently - turning off the low beams and turning on the high beams when the high beam button is pressed?

So what's the answer to the original question?

With dual headlamp systems, are both filaments lit when the high beam button is pressed the way they are in quad lamp systems?

Are you sure about that? I don't have an example, but on a 55.2 truck (2 headlamp system) and 59 truck (4 headlamp system) with the same switch and wiring, that can't happen. Maybe on SOME 4 headlamp systems that's true, but not on a Chevy truck.

The individual filaments are NOT on at the same time in a 2 headlamp system. Maybe done that way to prevent excess heat which would cause shortened life of the bulb.

Ok, Misunderstood your previous post. The dimmer switch is the same but the rest isn't.

So low beams are off when high beams are on in a dual headlamp system, correct?

That's what I'm understanding from looking at wiring diagrams. I recall seeing some 4 headlamp systems with all 4 bulbs lit, but that wouldn't apply to the '59-60 Chevys.

4 headlight system, inner headlights are dual filament, just like a 2 headlight system, and they operate the same way. The outer 2 headlights are high beam only, so...

Dimmer switch on low, you get the low beam filament on the inner 2 headlights.

Dimmer switch on high, low beam filaments shut off, high beam filaments on the inner headlights come on, as well as the outer 2 (high beam only filament)

Gotcha. I never knew that.

Mike is correct, only the dual filament bulbs go on the outside, so low beams are on the outer part of the vehicle.
I should have seen that on the wiring diagram I found here. Should have looked closer. Still separate low and high beam circuits, that are not active at the same time.

Outer lamps are dual beam (high or low) while inner lamps are high beam only like Kevin said above.