Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part JUNE's Ride of the Month Challenge!
  • May's Ride of the Month contest ended with a tie! Go to this thread to vote on the winner! VOTE HERE
1 - 4 of 4 Posts

·
Registered
Joined
·
2,193 Posts
Discussion Starter · #1 ·
I went to test a 68 fog light bulb by taking a couple of wires and connecting them to a battery and it suddenly started to smoke inside the light. Should I have not gone directly to the battery? Is there some sort of resister in a normal setup? Thanks
 

·
Registered
1967 Mustang GT fastback
Joined
·
4,019 Posts
Naw - just burned the light out IMHO- it's kapootski. The circuit does goes through a circuit breaker of about 10 or 15 amps, but still 12 volts. Just like testing a horn or wipers - connect them to + and - , then see if it works.
The smoke you saw was the tungsten filament frying due to heat buildup - resistance- in the tungsten filament itself. Resistance was caused by a thinning or crack in the filament. The thinning made it hard to carry the current from the battery, so it heated up and burned out at the thinning/crack point.
New bulb time.
 

·
Registered
Joined
·
357 Posts
Also make sure it was not a 6 volt farm tractor bulb. A friend gave me some old acc. lights with the rubber housing that came from a tractor, I tested them out the same way and the did the same thing. Took the bulbs out and on the back it said 6V
 

·
Registered
Joined
·
10,560 Posts
Electric lamps also do what he's describing when there no longer is a vacuum or inert gas inside
the bulb. End result is still "get a new bulb."
 
1 - 4 of 4 Posts
Top