Our '06 RX-8 has developed a problem where the radio is very noisy and won't find weaker stations when the heated rear screen is on. Turn off the heated screen and its fine.

Before I go tearing everything apart, any clues as to what I should check first?

Druid

 

I've not had this happen with my 8, though I've had it happen with a couple other cars. In those cases, the cause was the same: a weak battery. In the good ol' days of carbs, weak battery issues always gave plenty of warning because starting always involved many seconds of cranking and you could hear the slow down of the starter if the battery were going bad. Modern EFI systems work too well to give this warning of impending doom. A weak battery means the alternator is full-on all the time, plus a shorted cell means the alternator pulses won't be filtered by the battery as they normally are. So, in leu of more type-specific suggestions, take your car down to Autozone or Sears and have them give it a load test. Good luck!

 

It's fine with *everything* else being on so its not load related.

*just* the rear screen does it (which is also the aerial on the RX-8).

I've checked the battery through OBD and it reports fine, plenty of v! :-)

Druid