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Discussion Starter #1
The light works. I've tested it. However whenever I try to put it back on the switch...it always blows some fuse somewhere. Once it was the fuse right next to the one which the fogs go to. The next time it blew a fuse under the hood.

All connections (aside from at the switch...when it shorts something) seem to be secure. I see no damage to any wires..etc. etc.

Can someone recommend a starting point at trying to trouble shoot this?
 

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is this a new setup? did you use a relay?
 

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Discussion Starter #3
I installed it, quite well I thought. It ran for about 3 months before the passenger side fog stopped working.

Yes, there is a relay mounted to the side of the engine bay.
 

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Check where your wires go through any metal. At the firewall between the engine bay and interior and at the radiator support would be the first place to look. It sounds like a wire has been rubbing and has worn through insulation to the bare wire and it's now grounding on the chassis.
 

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First step is to verify if a short is present. Unhook power to the wire, and hook a ohm meter between the wire and ground. If you have continuity between the ground and the power wire (with the light unhooked) you have a short. If not wiggle the wires around to check for any change.

Second step is to verify how much power the light is pulling. I have no idea what kind of light it is, but many hid lights have capacitors and other temp storage devices to aid in starting the arc Inside the bulb. Such lights can pull a lot more power at startup then when running, causing blown fuses.

All lights should be powered through a relay. Relays can go bad and cause a short that blows fuses. It's rare and normally only happens with cheap relays, but it's something to consider.

Really it comes down to either a short, or too much amperage draw (due to malfunction, bad wiring, or overload). A couple quick tests will answer which one of those it is.
 

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Discussion Starter #6
Thanks. I'd say it's definitely not a worn wire but I will check at the firewall (checked everywhere else). Then I'll check the power from wire.
 

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Worst case scenario which may be easier is just run a direct line and then you'll know the whole route from tip to tail.
 

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I've had a bad bulb that shorted internally before. Try removing one bulb at a time, then swap them side to side to isolate the problem.
 
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