1992 BMW 525 radio wiring

RED / green = permanent purple = accessories brown = ground white = auto antenna some of those if not most had an amplifier in the boot. look behind the left or it could be right as in australia everything seems to be on the other side to the states. there you will find either a becker or blaupunkt amp. the only way i know if the amp isnt working is to run cables from the deck to the speakers, BUT the amp has the crossovers inbuilt and you will have to supply passive crossovers to the speakers. its the long way if you want to do it yourself or the option to take it into a store is also there. these cars arent the easiest ones to work on so unless you know 100% what your doing its best left to the pros.