rear running light problems

[maxwell91]

new to this site, have had this truck for 4 years drove for a year and blew it up just decicided to put a new motor in and am trying to work out some of the issues.

the fuse that runs my rear running lights keeps blowing. i have disconnected the harness in the rear, brake light switch, and my turn signal switch. Have ran a new line to the connector in the back of the truck for the running lights, Ive had the dash cluster out (since that runs off the same fuse) and still am having this problem. they were working a few weeks ago when the engine first fired. the fuse is blowing immedietly when turn the headlight switch. (wich is new too). i have headlights brake lights and blinkers.  maybe a front running light? i forget which lights are a normal running light. the trucks been sitting for 3 years.

~maxwell~

[maxwell91]

haha such a newb

the truck is a 1987 custom k20 no a/c with a freshly rebuilt 350 and a muncie sm465.

[Captkaos]

Does it have an aftermarket radio in it?  There is a whole post on this from about a 2 weeks ago.

[81_Chevy]

http://forum.73-87chevytrucks.com/smforum/index.php/topic,25166.0.html

[maxwell91]

no aftermarket radio

[pholliday1]

Specifically what Capt. is talking about is that there are wires that run from the headlight switch to the radio. "Sometimes" these wires become unhooked/not corrected properly, as a result of this if these normally "hot wires" touch ground they will blow the fuse for your lighting circuit. There are some very good wiring diagrams on this site which will confirm what wires you are looking for. Your in the process of elimnation phase and there are other items that could be causing your problem, Stereo wires generally make for a pretty good culprit.