I have an e53 x5, i ran an aux cable to back of the cd player a year ago or so and had the aux input working since.

last week the head unit stopped being able to switch to aux, it just goes between radio and cd when pressing mode.

i pulled the cd player, unplugged and plugged the cable back in, didn't work. as i was putting it back together i hit the mode button a bunch of time and it went to aux however this morning it wouldn't go back to aux.

does anyone here know the mechanism by which it deteremines if there's an aux cable connected? i used to be able to switch to aux without an ipod or anything hooked up to the cable, so it's not based on receiving a signal...

any thoughts or ideas?

thx