Can Someone Please Help. Blowing Fuses

[bandt]

Everytime I turn the marker lights on I am blowing a 20amp fuse marked MISC. in the fuse block. I had the problem once before put a new fuse in and it was fine for a while. Now its serious, no driving past 7:00 cause I have no marker lights. I still have headlights, but no taillights,radio, dash lights or marker lights. Is there a way to test the headlight switch?
 Sounds like a short somewhere, I don't even no where to start. Man I suck at electrical.

Thanks,
Brian

[Chryco Psycho]

Everytime I turn the marker lights on I am blowing a 20amp fuse marked MISC. in the fuse block. I had the problem once before put a new fuse in and it was fine for a while. Now its serious, no driving past 7:00 cause I have no marker lights. I still have headlights, but no taillights,radio, dash lights or marker lights. Is there a way to test the headlight switch?
 Sounds like a short somewhere, I don't even no where to start. Man I suck at electrical.

Thanks,
Brian

 You really need to start with a wiring diagram !Maybe starting at the lights is better , I assume you have an ohm meter , start disconnecting light circuits at the front & rear of the car until you do not show a short , zero ohms resistance to ground . The misc feed may feed the lights so I would pull the headlight switch panel & disconnect the feed to the headlight switch from the fuse block & check for power there ?
the short could be anywhere in the car , a misplaced screw into the wire or a wire rubbed through in a socket or in the trunk .

[bandt]

Is there a way to check if the headlight switch itself is bad.
 I just noticed that the key doesn't have to be in the ignition. As soon as you turn the lights on the fuse goes.
I think I have to break down and take it to someone, I'm not even sure what an ohm is, I don't know what I'm doing.


Brian

[Cooter]

First off, I can only ASSUME we are working on a Mopar..Further, I assume it's a Cuda/Challenger...Being that as it may, you need to first check the stupid sh*t like wrong Bulbs installed...You would not believe how many times I've seen this...(Single contactg bulb in a dual contact socket)..

If all ok, next would be the "Wiggle" test. Try to get at the wiring going to your parking lights. look for any frayed wiring, bad grounds, etc.

If all ok, THEN, and only THEN would I be looking at things like the Radio, Dash lights, and whatever else doesn't work..Think of electrical like Xmas tree lights. You can have one little, stupid thing cause all kinds of hell...FINDING that stupid little thing is why you will pay at a shop...

[bandt]

Thanks Cooter,
Your assumptions are correct its a 72 Challenger.

I know my bulbs are okay. Everything was working fine then one day a couple of weeks ago backed out of the garage went to turn the headlights on and that's that. Been doing it since.
I will try your suggestions.

Brian

[Chryco Psycho]

you can get an OHM meter for as little as $5 at princess auto . it measures resistance in a circuit , if you connect it across a bulb it will tell you if the bulb is good & what resistance it has , if it measures zero ohms it is shorted , if it measures infinite ohms the circuit is not connected ,
 I doubt you want to do this but I could fly back & help you , it would not be cheap but might actually cost less than taking it to someone & you would learn lots !!

[bandt]

Thanks Neil,

I appreciate the info. I have a crappy multimeter with ohms on it. I'll give it a try.

Why can't I have any neibours like you??

[Chryco Psycho]

I think Spirit air can fly me round trip for $400 or so

[bandt]

Thanks a lot for the offer Neil, I'm going keep plugging away. Hopefully I will stumble on to it.

[brads70]

Thanks Cooter,
Your assumptions are correct its a 72 Challenger.

I know my bulbs are okay. Everything was working fine then one day a couple of weeks ago backed out of the garage went to turn the headlights on and that's that. Been doing it since.
I will try your suggestions.

Brian

 I'd ask Jim ( Slotts) how to test the headlight switch?

[Slotts]

I don't think it is the headlight switch as much as it being the dimmer switch. The headlight switch is doing it's job.  It closes the circuit. How well can be another story. I have seen the dimmer resistor coils comes out of the tray and touch the switch frame. Pop goes the weasel.

Slotts

[brads70]

I don't think it is the headlight switch as much as it being the dimmer switch. The headlight switch is doing it's job.  It closes the circuit. How well can be another story. I have seen the dimmer resistor coils comes out of the tray and touch the switch frame. Pop goes the weasel.

Slotts

   great advice Jim! 

[MEK-Dangerfield]

Do you have a Rally dash? When the markers are on, they share the same circuit as the clock and radio. Do you have an after-market radio?

[ShelbyDogg]

This should be very easy to find since it is blowing fuses right away.  Get a spare light bulb socket and hook 2 wires to it to make it light up when hooked across your battery. The bigger the fuse you're blowing, the bigger the bulb you need. I use a tail light bulb for a 20 amp fused circuit with one wire soldered to the outside and the other wire soldered to one of the terminals. Hook the 2 wires across the fuse terminals that blow with aligator clips or just stuff them in there. Turn on the switch. The brighter the bulb glows, the more serious the short.  The light will be on BRIGHT.  My full 70 Challenger parking light circuit only draws less than 4 amps with about 16 bulbs on. So blowing a 20 amp fuse is a dead short to ground.

Start at the driver's side kick panel and unplug the harness to the tail lights. You eliminate the whole rear harness with this plug. Is your test light still glowing? If yes, unplug the plugs at the front turn signals, then the front side makers. Keep going till the bulb goes out and you'll find your short.  You can hook a small 12v buzzer across the bulb if you are by yourself tou "hear" when you find your short, if you are by yourself and don't have someone to watch the bulb.

Very easy to find a dead short. Harder to find an intermittent one.  The light bulb will save you many fuses while energizing the circuit and some of your bulbs will light up too.

[bandt]

Great advice thanks guys, been gone all weekend going to work on it again today.

Brian