2004 Homelink Problem

[Chancevoughtcorsair]

Had the homelink mirror installed on my early 2004 X3MT 2.5. Well not quite. Two BMW dealers came up with the same part # (51 16 9 174 309) . On paper it was supposed to work. When hooked up the homelink worked (as in it was powered) but the ignition keys no longer auto lock-unlock after being resynced. Apparantly the keys are tied into the mirror somehow with the unlock function. The tech was confident the key was not at fault and that it had not coincidentaly failed while installing the new homelink.
The second dealer tried three seperate homelink mirrors. But the only time the ignition keys would auto unlock/lock was with the orig mirror.
The orig mirror has NO autodim and the new homelink mirror has autodim.
My X3 was prewired for Homelink so the retrofit cable was not used.

Via another forum, a X3 owner had me contact his Dealer in IL. That parts guy came up with part 51 16 9 123 513. This is a homelink for a E46 convertible that he feels will work on my X3 . Both older technology both E series. Problem is these mirrors being 'electronics" tend not to be returnable.

What are we missing here? Could my prewired X3 harness be different than what the new Homelink mirror reqs? Is my orig mirror with no Autodim and the new Homelink with Autodim not compatible? All involved feel this should work but no one can hammer down why it doesnt.

Thoughts anyone?

Thanks
TODD P.