DriftVader

SO im completely stumped as too where too even start trouble shooting.

My car did run fine about 2 weeks ago. Now all of a sudden the car wont start if i have my gauge cluster hooked up and if I start the car with the cluster out, then plug it in, the cars RPMs drop and it sounds like a heavy load is beig put ont he battery. With the cluster plugged in the alternator is only generating 12.75V. With the Cluster not plugged in, the alternator does even charge, the battery just says 11.5V. Not sure if maybe my cluster jsut went bad, or what. But When i have the cluster plugged in, everyone on it works, just seems to be creating some type of heavy load on the car. not sure. any help would be great. thanks.