Just replaced all of the headlights in my '70 with halogens. Low beams work fine. However, when High beams are switched on, the low beams stay on - but dim quite a bit.

Any chance I need to replace the dimmer switch on the floor? Any other explanations or things I should check out?

Thanks!

Andy

Halogen bulbs draw quite a bit more current than the standard bulbs. If you're running them through the factory wiring and dimmer switch then that could be the problem. They weren't designed to handle that amount of current and you're probably experiencing a voltage drop. You could also possibly melt some wires or cause a fire. They should be run off a relay so the full current load is not going through your headlight and dimmer switch or old wiring.

Thanks Hank!

I'll have to look into a relay. The wiring is only 3 years old, but I'm sure utilized the old design.

Andy

Andy, Something easy to try: Ensure your headlight grounds are good by putting a "star" washer between each ground wire bolt eyelet and the rad support. They dig into the metal on each side and make good contact.

Thanks, Von!

Good to hear from you. Wish I was going to get to viisit with you at CB'05, but not this year!?!

I'll give the contact approach a try, too! Relying on the old headlight technology to get home from local cruises almost seems dangerous by today's standards!!

Andy

Andy, I wish you could make it too. I'll bet you'll be there next year for sure.

http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

Thanks, hrd!!

Andy

I added the relays, but I didn't cut the factory wiring... I just plugged in jumper wires from the headlight connectors to the relays... Eventually, I plan on getting some used headlight connectors to get rid of the generic spade connectors at the lights...

Works great...

You already got the star washer on the ground suggestion...

Look carefully at the grounds. The ground wires are critical for the headlights and use a smaller guage wire than the other headlight wiring. I found crimp-on terminals on my '68 on the grounds and both were absolutely fried. If there is any kind of resistance in the ground connection or the wire connection it can generate a significant amount of heat. We all have heater elements around and so can associate watts with amount of heat? Well the resistance in an electrical circuit dissipates watts in proportion to current *squared*. So if you had a 1 ohm resistance in the grounds and a 10A current, it would generate the equivalent of 100 watts of heat, 2 ohms and you are looking at 200 watts. This is how terminals and switches get melted.