My fuse blows when I put my GPS in the cigarette lighter, Why? on 1990 Chevrolet G Series Van (G30)

I put my GPS plug in and the fuse blows.
Is ther any way I can find out if the socket is bad?

1 answer
Does the plug from the GPS fit securely? Some plugs are not configured for domestic receptacles.
If the cigarette lighter works properly the socket is OK.....