Packard Forum Index » Pre-War (1899-1942)

Okay…I’ve figured it out with some help from a post I found on a Ford forum.

As the bulb is oriented in the socket, the bottom filament is the High beam and top filament is the Low beam.

So, by looking at which filament is illuminated and then removing the bulb to check voltages on the terminals, the bottom filament (High beam) is the Left Hand terminal when looking at the back of the bulb. (See photo)

It turns out my sockets were wired backwards. So, the first photo below showing the headlights is what I currently have as “low” beams, but this is really the high beam. The second photo shows what I currently have as high beams, but should be the low beams.

I need to switch the wires at my sockets

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If you ohm each terminal on the bulb to the bulb ground (metal housing) the low beam should have higher resistance than the high beam.

Some bulbs of that style are dual filament, single wattage (CP) Others are dual filament, dual wattage. I have one bulb that is marked 25-50. Others are marked 32-32 or 21-21.

The dual wattage bulbs will show different resistance on each of the filaments, the single wattage ones will not.

All correct. What I found is that in all of the dual filament bulbs of this type, the bottom filament is the high beam and the top filament is the low beam.

You just have to be willing to blind yourself for a few minutes to look. Then, you can remove the bulb and check the voltage on the terminals to see if the wiring is correct.

Just thought I’d provide an update….I’m still learning.

Part of the reason I had so much trouble discerning which beam was which just based of the pattern on the wall (cabinet), was because I didn’t have the headlight lenses installed.

When I got my car running, I installed the lenses. I didn’t realize how much of a difference the lenses make for the beam pattern!

In order, the photos below show City Driving (low beams), Country Driving (high beams), and Passing (left low beam and right high beam). Note…my left bulb is much brighter than the right. I just have very cheap bulbs installed for now.

The low beams aren’t quite as focused, but you can really see a difference in the height of the high and low beams.

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Funny thing is I remember when for your car inspection they actually checked your headlights beyond just working. I've also tried testing my high and low and have had trouble "seeing" the difference in brightness or direction. The OCD in me meant it bothered me until I realized that even if I drive with high beam it can't be worse or more blinding than most of the cars (and esp. some trucks) these days so I rested my anguish for good.

Yeah, it’s hard to imagine now why they even bothered with high and low beams back then. But, that’s today’s perspective due to how bright the lights are now that we’re accustomed to.

If your reflectors are good and the headlight assembly is in focus and wiring is correct, you can tell the difference. Most adjustments are to be made at 25 feet. Lenses must be in place. Correct focus and aiming makes a huge difference.