1997 Toyota Tacoma electrical problem....?

I just bought a 97 tacoma and after i drove it home i realized that neither the heater nor the cruise control were functioning. air blows from the vents but no heat, and the "cruise" light illuminates on the dash but it will not cruise. also i noticed that anytime the heater/ac fan is turned on, the ac on lights up, whether it is on or off. it is just the light, the ac works just fine along with the on. the truck has an aftermarket stereo installed and i cant help but wonder if all of this is tied into a poor wire splicing job behind the dash. any ideas on where i might find a wiring diagram online? or maybe this has happened to you and you could walk me through it? somebody out there, please help me, i live in washington and its too cold to be driving around without a heater... thanks