Dead Z3 Radio

Did you actually enter the code or just ignore it? If it was dead before you disconnected the battery first check the fuses. There will be two, one for the switched 12 volts to turn it on and one for the station presets memory when it's turned off.

Unfortunately these silly access codes benefit the dealer, not the car owner.

When you say "then suddenly does (asking for the access code), it sounds like you're saying it still never plays, it's just asking for the code at times and not at others.

Just so I understand, was the radio working properly before you replaced the battery? In your original post, it sounds like the radio was acting up, then after that, it started asking for the code after you replaced the battery. That would imply the problem is not related to disconnecting the battery. Two things come to mind. Some vehicles have a known history of fuses working loose and causing an intermittent connection. I'm not aware of that on your car, but it's something to consider. That, to the radio, would be the same as disconnecting the battery, then when the fuse made contact again, the radio would ask for the code. Second, all electronic equipment tends to develop intermittent solder connections. The pins in the electrical connectors is a common place for that to occur. That too would be just like disconnecting the battery.

A good place to start is by contacting the selling dealer to see if they recorded the radio code. To my knowledge, only Volkswagen dealers have no way of knowing the code. If the owner doesn't know it, that radio will never play again and must be replaced. GM makes it real easy to call in and get the code but of course they charge for that. It's just one of their many ways to continually bleed money from their owners. I don't know the procedure with BMWs but if it's like many of their other business practices, you can plan on needing to visit the dealer. If you have a friend who is a mechanic at the dealership, he might be able to get the code or know the phone number to call.

I don't want to throw a clinker in the works, but from the way you described it, I suspect there is a problem in the radio itself. I only repair original equipment radios but manufacturers have stopped allowing me to buy their parts and service manuals because I save people too much money. That means I can pretty much only work on Chrysler stuff now. We aren't even allowed to know the paint codes for BMWs. If they keep that secret, you can be sure they don't want me fixing your radio.

I would like to hear back that I'm wrong and a code is all that's needed, but the dealer would be the place to start.

Any luck on this one yet? BTW the Dr. Is in the house

Aftermarket stuff has much more to offer, and there is a package that will allow the use of specific aftermarket equipment and that can interface with the changer in the trunk and the wiring harness in the car without cutting into the radio wiring harness. Cats are seeing the vet today and (most) all is well, thanks for the concern mate!

Welcome Back Cat :-)

Back in the saddle again.

Crutchfield sells a wiring kit that will allow you to plug an aftermarket head unit directly into the stock harness. They also have a fitment guide that will allow you to purchase a head unit that is an exact fit. Both will come with full, detailed and illustrated instructions. From my recollection, if you buy both at once, they will also ship an installation video.