1994 Sable 3.8 PCM location

My 94 sable GS has 32k miles on it and it just recently died electrically. Engine still cranks and makes compression however nothing electronic works on it. Windows, lights, radio, horn all dead. I'm thinking of replacing the PCM on my Sable. My question is where is the PCM also should I be concerned about replacing something else. I read somewhere of an IRCM or integrated relay control module. The weird thing is when i turn the ignition to off I get a constant check engine, ABS, and battery light that won't turn off untill i disconnect the battery.And the engine still cranks. Please someone help me. Thanks in advance.