Cigar Lighter 55 Cadillac

[Bob Kielar]

Is there a capacitor or something that screws onto the back of the lighter or does it run directly off the battery. I got a used one and is has this round little can that screws on the back of the lighter and you can put your 12volts to this but the lighter does not work with this connected but does without it. Is it necessary ?

[35-709]

There is no capacitor, the "little round can" is what is screwed on to the lighter assembly from the back after the assembly is inserted in its mounting hole.  That is what holds it in place.  If you put 12 volts to that "can" once installed you may well create a dead short --- it will let you know right away. 
Geoff N.

[J. Gomez]

There is no capacitor, the "little round can" is what is screwed on to the lighter assembly from the back after the assembly is inserted in its mounting hole.  That is what holds it in place.  If you put 12 volts to that "can" once installed you may well create a dead short --- it will let you know right away. 
Geoff N.

Geoff,

Actually that metal piece should be the in-line fuse for the Casco type cigarette lighter, which screws onto the lighter stud. These type of fuses are rare and $$$, alternative would be to splice a new AGC type in-line.

[35-709]

Thank you, Jose.  I shouldn't assume all lighters are the same as the ones I am familiar with.
Geoff N.