the factory specs indicate that the 3-pin pre-wired connector was wired up behind the screens since the 10/2002 production date... without that connector, we need to get into the BM54 directly... depending on the date of the BM54, you might not have the AUX input available/activated... if that is the case, we would need to bring into the picture the heavy guns...

There is guy soomewhere in the UK who is the GURU on the BM53/54... his name is Boris or Baris, not sure... but he can upgrade the firmware on the radio, activate inputs, add some features... he has a website and is very responsive in his emails... before bothering him, lets see if we can manage without disturbing the man...