Lennybadger

Ok, without going into a lengthy thread I will just giv the basics. I installed a pioneer navigation unit. Everything was fine for a year. The heat went out on the car. I quit driving it and bought a beater. Started having weird electrical issues with the clk. The battery went completely dead and sat that way all last spring. When I went to get it running again all the power accessories work but turn the key to start and it did nothing. I couldn’t hear the starter or fuel pump it was like it was dead. Took to a shop where they diagnosed the pcm being bad. Replaced the pcm and still won’t start. Now being told it’s because I replaced the factory radio. They r saying it’s part of the security system and that’s why it won’t start. Truth? If so, why did the car run fine for almost a year? I posted in the w209 section but thought I might get more info here