something is killing my battery

[waynep]

over the last few months something in my 1990 Chevrolet is killing my battery. I am not a electrical trouble shooter but if I could get some direction may I could fix it.

I backed my truck outside last week and it was dark before I put it back in the shop. while walking towards the truck I could see something inside the truck was lit up. when I got inside the face of the heater control was on. The lights were turned off and the keys were not in the switch. This is what I suspect is draining my battery. after pushing several buttons on the controls the lights went off and I could not duplicate the problem again.

Any thoughts or suggestions?????????

[Second Series]

Key switch? I noticed the aftermarket radio in my '90 k1500 stays on sometimes after I turn off the key switch. I have to wiggle the key cylinder to get it to power off.