1987 Chevy, driving along and the fuse(size 20 T/L CTSY) blew for the dash and tail lights. replaced the fuse and it blew up also as soon as you turn on the headlights. Anybody got any ideas? PLease!
Do you have a wiring harness for a trailer? If so, that would be the first place I would check.
You need a test light and a continuity tester. Find the plug that takes the wiring back to the rear lights and unplug it. It is behind the kick panel left of your left foot on most cars. Now replace the fuse if your dash lights now come on you know the trouble is in the wiring to the rear lights or the lights themselves, Unplug the tail lights and check the continuity of the taillight wires, If one is no good you can look for the short or just run a new wire. You usually have one wire going to the left rear taillight , then one going from the left to the right. If they are ok put the front plug together ,then plug in the taillights one at a time starting with the left and see which one blows the fuse. If there are no plugs to disconnect at the lights you will have to pull the bulbs instead.If your front parking lights are on the same fuse you will have to deal with them in the same manner. The comment above about a wiring harness is spot on also.