[dataway]

I'm rebuilding the OEM headlight switch in my GTO ... surprisingly they appear designed to be serviced. Opens up easily, comes apart and goes together in a straightforward fashion. Several components look like they could be replaced.

Anyway, inside the case is the object shown below, which appears to be a circuit breaker. There is nothing mechanical that appears to interact with this set of contacts and from the discoloration it appears it might be a bi-metal over current circuit breaker.

Goes from pin 1 (which looks like main power input) to the contact points for the headlights.

Anyone have any knowledge of what it is, or how it's intended to work? I've never heard mention of a circuit breaker inside these switches.

["QUICK-SILVER"]

I think most all (domestic) headlight switches had the circuit breaker built-in.

Newer and foreign cars, that the headlight switch trips relays, didn't need/didn't have the built in circuit breaker.

About the only circuits that didn't have secondary protection, beyond the fusible links, is starter solenoid and ignition.

Clay

PS Be thankful it's not a Ford headlight switch leaking automatic transmission fluid.

[OG68]

As Clay mentioned, most domestic cars had an internal circuit breaker as part of the headlight switch. And you are correct with the bi-metal contact. It works on the same principle as the turn signal flasher. Excess current through the bi-metal contact causes it to bend slightly and open the contacts. As the metal cools, it straightens out and re-establishes contact.
This way if there is a shorted headlight or wiring, the headlights will go on and off. I have found that the headlight was usually the problem and by unplugging it I was able to continue driving at night.

[dataway]

Had no idea .... well, I'll clean up all the contacts, put some fresh grease in and put this back together.

Wonder if I should use something like lithium grease on the mechanicals and di-electric grease on the sliding contacts? Or leave the sliding contacts dry?

I'll be using LED headlights so amps should be way down compared to stock.

[Formulabruce]

Back in the later 70's folks tried to update headlights to
Halogens, etc with no relay. Adding amber fog lights behind the grill on low beam was a thing too. We ended up ordering these to the point that AC DELCO called our parts guy to ask why. Have seen these fried bad and melted too.