This last weekend I installed an Alpine iDA-X305S into my 04 Mini replacing the original non-HK head unit. I purchased the head unit replacement "kit" from Crutchfield which included the wiring harness, antenna adaptor and mounting brace. I used the wiring diagram posted by DarkMiniCooperS in this thread. The installation was fairly typical and relatively easy.

The issue I'm experiencing is that when listening to the iPod through the Alpine HU everything works great but when I switch to FM (FM1 or FM2) I do not receive a signal from any station and my turn indicators do not flash. I can turn up the turn signal level or push the hazard switch, but the lights do not flash either in the car or out. When I change the source back to iPod on the head unit, the flashers come back into operation.

I suspected the antenna might have something to do with this problem since changing the source to FM replicates this issue but even with the antenna disconnected from the head unit it still persists.

Does anyone have a clue what could be going on?

 

Your link got messed up. I think you meant this.

The only way I could think of a headunit affecting turn signals is through bad interaction on the data bus. See if the turn signal comes back if you disconnect the wires on pins 9 and 10 on connector A. Also double check that all your connections are correct on connector A.

 

Thank you for the correction in the link. That was indeed the thread I was referring to.

Pins 9 and 10 in the diagram indicate CAN+/I-Bus and CAN-/T-Mute respectively. The diagram also explains that Pin 9 is "used as a security check before the unit is allowed to power up". Neither of these connections however, translated to any of the wires from the Alpine Head Unit. I believe I left both unattached with caps over the end. Do you know how Pins 9 and 10 should be wired in the case of an after-market head unit upgrade?

 

Typically pins 9 and 10 would not be connected to an aftermarket headunit except for using the steering wheel buttons (usually an additional interface box required).

So that leaves me baffled about how your headunit could affect the turn signals.