So I've been having problems with electrical stuff on my 1978 Z28. Gauges won't work, headlights won't really work and windows won't work. I'm trying to tie up every loose end. I found this plug sticking out with purple, blue, light blue, and tan wires on it. Can anyone tell me what it's for?

 

It is almost impossible to know this kind of information without personally being familiar with that year car or having a wiring diagram to refer to. The best help I could suggest would be to find copies of a factory service manual or wiring diagrams for reference. They are a worthwhile investment if your planning to restore the car the back to an operating vehicle. Here's a link to several Ebay auctions for a book with the factory wiring diagrams that may help.

 

Thats your Blower connection to blower switch.