Cig Lighter Fuse Keeps Going Out

Hi,
 
I got a GPS system that hooks into the ciggerate lighter for power. It worked fine for one day but the next day wouldn't. I checked and sure enough the fuse was blown. Put another one in and it worked. Until today.
 
Any ideas on why this is the case? The GPS works fine in several other family member's cars without causing any fuse damage.
 
BY THE WAY, I also hooked up my new radar detector and the same thing happened. Any ideas?
 
Thank you in advance.
 
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hi, do you have one of those adapters that has 2 outlets or you're just plugging the gps directly in the cig. lighter?

There are three things on that circuit, which is protected by a 20 amp fuse:  The cigarette lighter, the front accessory outlet and the rear accessory outlet.  If you have things in all three locations that add up to more than 20 amps, then that will blow the fuse.  If the only thing you are plugging in is the GPS, make sure it takes less than 20 amps (I would think it would), and if you still have the cigarette lighter itself plugged in somewhere, try unplugging it.

Oddly enough, the cig lighter fuse blows without anything plugged in. I do not use one of those double plug adapters.

Hope that helps. Thanks.

There must be a short somewhere then.