New headlight switch smoking

[WOLF DOG]

I had a problem with my Deuce burning up turn signal switches on the steering column. I would install a new signal switch and as soon as I moved the arm to test, a small puff of smoke would come out of the signal switch. I put a completely knew front wiring harness on and burnt up two more signal switches. The last switch had a soldered connection burn loose inside as the insulation on the tiny wire was burning. Only one more place to check that I could think of, the flashing unit mounted to the drivers side fender well. I tested the three prongs to ground and I believe the common prong had a dead short to ground, it been years since this incident so my memory may not be perfect. Anyway I acquired a new flashing unit, connected it, tested my blinkers, and all was good.

 

[G744]

A three-lever switch is a sealed, waterproof unit.

If there is enough pressure built up inside to get smoke past the O-ring in the crimped together housing I'm amazed.

I've seen them almost melt from shorts on certain circuits, even with the internal breaker.

DG

 

[WOLF DOG]

Yes, I agree G744. My smoke came from the blinker switch on the steering column, probably out of the hole were the green cover is.

 

[G744]

Yep, the regular Mil-Spec turn signal switches are of a really pis-poor design. They will barely handle the load of just the onboard 4 lamps. Add a trailer with increased load, or an intermittent short, and the switch contacts are toast long before the internal breaker in the master light switch will function.

I've gone to placing relays in a sealed box, one for each power wire going to my trailer plug, with a 20A breaker back to the batteries for the necessary 24V. At least with this arrangement, the box breaker will pop and I know the problem is downstream. It saved frying many turn switches.

DG

 

[Action]

Would badly corroded light bulb sockets cause this? Basically, the positive and negative rusted together. The front composite lamps seem to like holding water inside.

 

[G744]

Pressure washers get water into places it doesn't belong.

DG

 

[TOBASH]

Delete

 

[WOLF DOG]

Thank you for simplifying the diagnostic process TOBASH, I'm just a retired industrial electrician, not a surgeon.

 

[TOBASH]

You’re quite welcome given I have no idea what your talking about.

I guess you don’t like the word “deleted”???

And before I was a surgeon I put myself through school working as a mechanic and auto restoration specialist.

And no matter who you are, nothing wrong with the advice to clean and verify everything. Every pin connector, every ground strap, and every wire on an old used FMV.

 

[WOLF DOG]

You’re quite welcome given I have no idea what your talking about.

I guess you don’t like the word “deleted”???

And before I was a surgeon I put myself through school working as a mechanic and auto restoration specialist.

And no matter who you are, nothing wrong with the advice to clean and verify everything. Every pin connector, every ground strap, and every wire on an old used FMV.

Thank you for the advice you gave before you deleted it, and I do agree with your procedure.

 

[Warlordfrog]

Going wire by wire looking for ground or short. The engine starts fine and S3 is functioning well. It clearly an issue between switch and lights. I am spending a lot of time with the multimeter theses days. Thanks for the insight and perspective on this. I will keep you posted.