When replacing a new head unit in a 1994 Chevy Cavalier why will it only work when the yellow battery and red accessory wires are crossed all together?

Answer 1

Normally this means you have a short or a blown fuse. Check your fuse box and more than likely there will be a blown fuse if not you have a short in your factory harness or after market harness. If all else fails run your yellow (constant power wire) to the fuse box. Run it to a fuse that operates even when the car is off (horn). Runnig it like that will not harm anything, I've been doing this for 15 years! ALSO MAKE SURE THAT THE RED AND YELLOW WIRES ARE NEVER CROSSED BECAUSE THIS WILL CAUSE A DRAIN ON YOUR SYSTEM BECAUSE OF A BACK FEED TO THE IGNITION SOURCE