Is it common for Stock HU to go out completely?

[UpOn3]

I bought my car with the stock HU and it didn't power on at all. Part of it would light up with with the headlights on, that's it.

After I bought another HU of the same model, that one didn't work either, so I'm wondering whether it's the HU or something else. I tested the power and ground and they are fine. What else can it be? I see one two wire harness from the HU that's not used. The other two wire harness, that is plugged, is for the power antenna I believe. If I supply power and ground, shouldn't CODE light up when I turn the ignition to II and turn the radio On?

I want to make sure it's the HU before I send it in for repair. Thanks.

[ecsk]

A lot of HU require all 3 wires (permanent 12v+, ground, ignition 12v+) connected in order to power it on.

I assume you mean you have permanent 12v+ and ground connected, how about the ignition switched 12v+ ????

[UpOn3]

It was the switched hot wire that I tested. any ideas which is the constant one on a CM5908? The one that is disconnected has two wires, a blue/brn stripe and a wht/brn stripe.

[ecsk]

What has been disconnected ? from the radio side or from the car. can you post some pic to show your problem ?

Would this help ? constant one on a CM5908 should be yellow wire.

http://forums.bimmerforums.com/forum/showthread.php?1462263-definitive-guide-to-CM5908-radio-in-87-cabrio