Can a bad flasher blow a fuse?

The flashers on my 73 Gremlin blew their fuse today. I have ruled out any accessories that I have hooked up so that leaves the turn signals and back up lights. This happened on my way to a car show so I haven't had time to poke around too much but I have been wondering. Can a flasher going bad cause an internal short?

No. The flasher unit is an inline switch. All it does is make and break the circuit. Under normal conditions, the lights can be on all day long without popping the fuse, so you have a short somewhere in the circuit.

Does the fuse blow if you step on the brakes? If so, the problem is with the rear lights. If not, the problem is with the front lights.

Ya I have some investigating to do. I was kind of thinking out loud. A few years ago the fuse was blowing because the metal flasher was touching something metal under the dash. I assumed that was the problem this time. I was supprised to see it wasn't near anything metal. I ruled out the accessories as when I plugged them back in the fuse didn't blow. It was either the back up lights or the flashers. I just thought if flashers were known to short when they got old I would assume thats what happened.
I will find some time this week to get under there for a better look. I need to remove the tray that is under the dash to really get to the wires. If that looks fine I will start checking sockets.

Hi,

It is possible as non solid state flashers(all old style) are a Bi-Metal that completes the circuit, it heats up from the current load and because of the two dis-similar metals it will cause it to flex away from the side that expands less thus pulling it off of the contact. Possibly the metal is contacting the case as the case is contacting ground? Not very probable but possible. I cannot see how the metal could draw more current as it is completing the circuit thru the light bulb so current draw should only be as much as bulb draws. A bulb that is bad could do it if the filament fell off and re-contacted differently. Again not very probable but possible.

I see George said something similar as well as checking for some ground feedback etc. from something not being connected correctly.

 Odd things happen. I had a brand spanking new rotor(on crappy old Datsun mini truck) that shorted thru the dielectric to the distributor shaft via the pin that was holding down the rotor blade. Had just tuned it up, going down freeway and it dies, like what the heck, I have power and coil is sparking... I said OK let me try something that should not be it, luckily had old rotor, put it on, it fired back up. Took rotor back.

Possible old wiring... Old wiring can and does build up more resistance as it ages depending on conditions and if any overloading/overheating has happened etc. Check that maybe.

Other Info: Alternator flicker problems I have encountered in the past can probably be attributed to aged wiring that has changed resistance from stock spec which can change the apparent load on the regulator.

OK, Good luck!
Blitz



Edited by Blitzman - Jul/17/2016 at 2:38pm

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