Chevrolet Repair: Fuse, lamp bulbs, power contact

Question
my 20amp Park/lamp fuse keeps blowing out when i turn the parking lights on and have no idea what the cause is.

Answer
Pull all the park lamp bulbs out, and inspect the sockets for loose wires and shorts.\
While they are out, replace the fuse, and if it doesn't blow when turned on with all the bulbs out, start reinstalling them one at a time.
My guess is you will find a socket with a loose wire inside, touching ground, or a bulb base touching the power contact.

Van