Theres a short somewhere in this 62 mercury I have. Ive searched all over for it but I cant seem to find it (just based off appearances.) Keeps shorting out my blinkers. What can I use to find the short in the line? Im getting sick of replacing the fuse.
I assume it is the original wiring, not a replacement or universal harness. Well, you could sacrifice a few fuses to see if it is right only, left only or both. You could also unplug all but one at a time and see if it keeps shorting, which would tell you if it is just one that is giving a problem. Is it only when you drive the car, or when it is stationary and they are used as well? If only when driving that could mean the vibration connects a bare wire to metal somewhere near it. Have you checked the flasher, and it's connections? Corroded or loose? Has the sheathing on the wire become brittle and cracked off? My 56 Ford had just that happen to almost all of the wires for the flasher. Since the wiring is pretty simple in older car, you could carefully inspect the wires, giving special attention to places where they pass through, under or around things, as these places are more likely to chafe and break wires.
If you know which wire it is but don't know where what i do is add a light bulb in series. Cut the wire and connect each end to the pigtail of a socket. When you replace the fuse if it isn't shorted the lamp won't light up, then start jiggling the wires until the lamp comes on - it won't burn the fuse as the lamp provides resistance. Try to place the lamp so you can see it from wherever in the car, when the lamp is lit it is shorted.
My dad was a mechanic all of his lie, he used to put a 1/4" bolt in place of the fuse and look for the smoke. I know this sounds scarey but it works, have a couple buddies help you looking for the smoke. Remove the bolt with needle nose pliars because it will be HOT. Do not recommend doing this on any car with a computer
Sounds like a good way to melt your fuse block or burn your car to the ground. Other than that, it's a fine way to diagnose a short.
It's called the smoke theory of electricity. It is the smoke trapped inside the components that make them work and when the smoke escapes they quit working. Make up a 12 VDC bulb with short pigtails soldered on and aligator clips on the wire ends. When you have a short that blows fuses faster than you can change them just clip the bulb across the fuse holder and when it shorts it will light the bulb. Even a direct short to ground won't burn up the wire as long as the bulb is lit. Now go down the harness an wiggle until the bulb goes out and you will locate the short.
I laughed when I read this , my buddy did this all the time. He'd tell us "If ya don't see the smoke right away just wait a bit when she bursts into flame it easier to spot".
I use the light bulb method too but I substitute a 12 volt buzzer, then you don't need to keep an eye on the bulb. Gets annoying if you don't find the problem quickly. I remove all the fuses and start putting them in one at a time till I find which circuit has the problem.
I thought the old smoke test had gone away but here it is again. Think about it would you do that in your house to? Are your brakes lights still working or does that blow the fuse too ?
It is the original wiring so Im not surprised theres a short. I havent checked the turn signal switch yet. Thats a good idea. Ill look into it after it stops raining here. I followed the line as far as I could, through the frame, under the scuff plates all the way through the trunk but just didnt see anything that stood out. How hard is it to totally rewire something like that? I do want to learn how to do that. I need to get my head around how electrical works.
That smoke technique does sound interesting... but could also be potentially bad....? Id be more up for trying it out if I had a better idea about electrical current through the car... The bulb and buzzer idea sounds cool too.... and relatively simple. Im going to give that a try at some point.... Now talking about rewiring the car has kinda got me excited to do that. Whats the best way to learn something like that? and different resources ?
An answer to this question would clear up a few things since brakes and direction lights use the same wires. And, could have saved you some time digging.
The brake lights do still work. And when the power is just on the signals still worked. When I start the car and try them the fuse blows.
Well thats what I meant about when just the power was on (and not the engine). I should have clarified.
when i was a shop fore men had a mechanic from canada that hooked up 110v ac to check for shorts always worked if he didnot see smoke short would be gone then he just rewired that circuit
Do you have a book or anything that would tell you what else might be on that fuse?? How many blinks will they make before it blows??
I do have a service manual so Ill thumb through that and see what I can find. It last a few blinks with the car "on". but with the engine started it shorts right out.
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