A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
For intermittent problems like yours the bulb may be dim already. Watch what takes place when it gets bright. That's when the short is occurring. If there's interior lights in the doors, there may be frayed wires between the door hinges. Opening and closing the doors may make that act up.
The ideal goal is to get the short to occur all the time, then you can unplug the radio and move things around to see what makes it go away.
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Friday, October 11th, 2013 AT 2:14 PM