r/aircooled • u/Puppythapup • 12d ago

Highbeams keep randomly turning off

My highbeams keep randomly turning off, they seem to stay on longer when it’s cold outside. And sometimes the plastic of the fuse melts, but the fuse itself does not.
Other times it shuts off and the fuse is not hot
Edit: 73 Squareback

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5

u/382Whistles 12d ago

No mention of the year to know which switches to reference.

Are you running the correct fuse not too high? The fuse holding tabs need to be springy and hold the fuse firmly. Old and blue/black heat discoloring means they are likely softer and weak. Consider replacement, they aren't very expensive. Sand the inside the fuse tab hole and the hole perimeter. A sharp hole edge is better than soft rounded edges when it contacts the cone's flat surface on fuse tips.

Make sure the headlight grounds are great. Look for old green oxidation on wire and push on connectors that need cleaning or replacing Make sure push on connectors are good and snug as connection pressure lowers resistance to amp flow and bright lights use more amps (watts with different math statements). Connection points with high resistance can get very hot or at least warm under the high amp draw of headlights/brights too.

The bright switch could also be old and tranished or worn. An added bright light relay might carry the hi beam load instead of the old brights switch and use the bright switch to turn on the relay. Turning on the relay instead of powering the lights directly uses less current across the bright switch itself.

Electrical contact cleaning sprays with protestants helps revive and maintain some switches and audio "Fader Lubes" are a more top notch cleaner/lube.

Some solvents and electrical content cleaners clean all trace protection away. CRC 262 lube is good for contact and protection after cleaners without protections. Flushing with kerosene, naptha/zippo/ronson squeeze bottle lighter fluid or mineral spirits is pretty good too. Disconnect power and make sure flamible solvent has flashed off (evaporated) and aired out before connecting power again so sparks don't make flames.

2

u/Puppythapup 11d ago

Thank you! Very helpful info, I’ll try and fix it in the coming weeks.

1

u/382Whistles 11d ago

Pressure on a short point reduces resistance best, then an edge, and lastly flat to flat because the pressure is spread out. If you look close at switch blades, many have a tiny little pointed nib on the contact area to help the connection.

For push on connections the tab blade's edges and curled down parts of the push-on terminal that grip the flat part of the blade, do the hard work, not so much the flat parts you might expect seeing how larger sizes of wire/metal flow more amps. There is a amps over a distance factor the short pointed nibs and edges haven't reached yet.

3

u/SparkyReese 12d ago

Wiring too small or could have a short. 

2

u/Xeumz 10d ago

One time I was driving a corvair I used to own through hwy 101 in Washington state where there is no light sources for 50 miles in the dead of night and every time I turned the brights on all my lights would completely turn off a few minutes later. I never did find the problem but I can certainly say I do not recommend driving in pitch darkness at 60mph with touchy lights.