2006 R50 built in Oct. 2006, base Hatch. The radio is dead because its constant 12V power from battery is dead. 10 amp fuse on radio is good, two radio fuses in interior fuse block are good. Engine compartment fuses are good, though I did not check fuses or relays on underside of the engine compartment fuses/relays. Everything else in the car works including the cruise control. There is a fuse, F5, that is intact, but only reads at about .5 volts. Don't know if this is okay or what that fuse supplies voltage to. Can someone tell me the routing of the 12V wire in question. It is wrapped in a bundle, hard to trace unless I unwrap the whole thing. I am hoping that someone can tell me where it goes after the radio, whether to a connector, relay, or anything in its path toward the battery12V constant.

Thanks for your help.

 

I only narrowed the problem down as far as identifying that the constant 12V wire between the fuse panel and the radio was an open circuit, somehow. I just cut it at both ends and replaced it with a new wire, left the loom intact with the dead wire inside. Radio works fine again. I was not willing to put all the effort into doing a post mortem to how and where the exact problem was, but I curious. The car is all stock, clean, no altered wiring (until now), connectors that were accessible were good, no corrosion, etc. Wires were all fastened down and wrapped by the factory. I read more than one trouble shooting post on other sites that described my symptoms and then asserted the radio or power amp are dead, replace the radio. I'm glad I gave it a few days of tinkering and thinking, and testing with the multimeter.