hey all...car is a 54 packard clipper... it keeps blowing the fuse on the headlight switch when i try to turn on the lights...at best...it will light up and then die within a few seconds. the car was converted to 12 volt at sometime. and i figure it worked kinda well because the lights were working up until a few days ago. now every time i turn on the lights, the glass fuse on the headlight switch blows out. looks like the flashers, bulbs and even the switch was replaced when it was converted. the wiring to the switch looks all newer with modern connectors and wiring. the car had only 1 tail light working when i got it. i replaced the tail light, and then one of the front parking lights stopped working. but all the while the headlights would work. now, nothing will stay on. I still do have stop lights when i push the brake pedal tho. where do i start? could this be a grounding issue? i figured with all the lights running it was overloading the switch somehow and killing the fuse. i took out the parking light bulbs and still the headlights would not come one because the fuse had been blown. any insight or assistance is appreciated....i know this means i probably have to chase all wires and see where they go etc etc. the nice thing about the switch is that everything is labeled (dash, tail, head, prk). also, there appears to be some sort of silver rectangular module in between the hot lead and the power for the switch...i figure its something to help with the conversion from 6 to 12 volt. sorry for rambling, but i wanted to post as much info as i could.... thanks
The silver module is probably a self resetting circuit breaker. The fuse blowing is probably caused by one of the wires shorting to ground somewhere. You can try to isolate it by disconnecting one wire at a time, that goes out of the light switch. If one of them being disconnected makes it stop blowing the fuse, then you might have a short in that circuit. Inspect the wiring carefully from one end to the other, also inspect the light sockets (and bulbs) carefully. Thanks for the complete description of the problem, it really helps
There's probably no BETTER advice for a plan-of-attack to your solution than what squirrel has said above. DD
awesome suggestion! i will try that tomorrow and see where it gets me. i will report back later....thanks squirrel!
How big is the fuse you are using? It should be at least a 30 amp fuse. Unplug all the lights and see if it is still shorted out. If not re-install one connection at a time until you do find the shorted part or wire.
That happened to my'34 coupe a few years ago. it turned out to be the rheostat that brightens and dims the dash lights. It got rusty from moisture and sitting. I replaced the switch,then cleaned up the old one to use as a spare. Once I cleaned the rust off and put it in a friends car,it worked just fine.
DO NOT put a 30 amp fuse in the light circuit! If a 16 gage wire is shorted, the wire will melt and destroy stuff, before the fuse melts. Fuses are there to protect the wire. Use the correct size fuse!
if you have Halogen bulbs you may have to go to a relay spent a lot of last year dealing with problems on a car that was 12 volt but had aditional loads on it and had to use a lot of relays
Remember that the dimmer switch is in the head light circuit. If you have brake light you should also have dash lights. They are usually on one circuit, if you don't have dash lights then you don't have tail light on most of the older cars.
I had to do that on my ot pickup because it was burning out dimmer switches all the time. Along with following what Squirrel suggested check the wires running to each light for spots where they might have rubbed enough so that the insulation is worn off the wire. That includes any place that they go through a panel or over a sharp edge. Check the wires on the headlight that quit first as the problem may be in that circuit.
Squirrel just posted to not use a 30 amp fuse in the headlight circut. This is a large circut with a large amp draw. The factory hasn't used a fuse in this circut for years. The factory uses a circut breaker usually built into the switch. On initial turning on of the headlghts there is a spike in the amp draw due to cold filiments in all the bulbs. As the bulbs heat up the resistance increases and the amp draw is much less. A fuse of maybe 20 amps would be fine if the amp spike didn't blow it first. Squirrel is right about 30 amp fuse being a little too much for the 16 gauge wires but a 12 or 14 gage wire to the headlight switch would be better suited for conventional bulbs. Actually 18 gauge automotive wire is rated up to 30 amps according to my charts. old glass tube fuses will blow almost instantly where as a circuit breaker takes up to sever seconds in some cases and then will cool down and try again . If the headlight circuit shorts on bumps etc then you don't loose your lights completely and may get you home.
well..i havent made much headway as of yet... just to clarify tho...the fuse IS a glass 30 amp fuse. and it blows almost instantly when i turn on the switch. i disconnected the headlight lead from the switch, and the fuse stil blew. after that i tried disconnecting the tail and dash lights (inadvertently crossing wires and forgetting where they went), and reconnected the headlight wire, but the funny thing is that it STILL blew the fuse with most of the wires disconnected. i have a friend coming over who is good with wiring, so i can at least decipher which wires go where, and try to trace the problem that way. As i stated above, the lights worked least week , nothing has changed with regards to wiring (i havent moved any wires or noticed anything fraying/ rubbing) at least with the wires that i have been able to visualize. the wrapped harnessed wires also look intact. i am leaning towards the switch as the weak link. but i want to prevent this problem from happening again. should i try and run relays at least to the headlights and taillights? i figure these are the lights that draw the most power, the parking lights are smaller..... also, is there a generic type of headlight switch that i can try? thanks for all of the great replies!
just hunted around on ebay, and found a headlight switch that looks identical to mine... labeled as a 6 volt switch!! is this one of those (matter of time) issues, where a 6 volt switch would eventually die from being used in a 12 volt system,? i see some 12 volt switches listed for hot rod applications.....maybe i should just pick one up for piece of mind?
12 volt systems run half as much current as 6v systems. Power = current X voltage so if you have the same amount of power, you only need half as much current with twice the voltage What that means is that a 6v switch won't burn out because you're putting 12v thru it. But a 12v switch might burn out if you use it in a 6v system, because it's getting twice the current load. You need to look for shorts in the wiring, if it blows the fuse when the headlights are the only thing connected, then look at the wiring to the dimmer switch, also the wiring from the dimmer switch to the headlights. You can also disconnect the wires from the dimmer switch and see if it still is shorted.
The fuse still blew when the headlights were disconnected. And it also blew when I disconnected the dash lights. I also Noticed that the tail lights weren't connected either. So Basically the switch fuse still blows when there's nothing connected to it.....
If it's still blowing with nothing connected, it must be the switch. A contact may have come loose and is touching the case , but you can check this with a meter on resistance.
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