hi, i have a 1987 Chevy Astro and when i turn the lights on all the gauges on the dash mess up and my stereo shuts off along with every thing else in the interior. when i turn the lights off the stereo deck will turn back on but then if i turn it up just a little bit the deck automatically shuts off and back on. when i use the turn signal the interior electronics and gadges will turn on and off as the signal turns on and off. i have no idea what could be the problem can you please help? if you need anymore information please tell me. and please don't suggest i go to a mechanic cause i like to work on my cars myself thanks!

 

Problem starts only when the headlights are turned on!
I would check the headlight circuits first. They must be crossing with other wires in a harness.
I had similar problem on my 1987 Astro.
I had to replace the switch itself. on the column.