Install aftermarket head unit but still retain Onstar function

[viewmax]

I from reading some posts here it seems like the Onstar system work though a VCIM which appears to be an individual component and not part of the radio.

If this is true that I can replace the radio/cd/dvd/boes system with an aftermarket head unit and still keep the On star functionality... are my assumptions correct?

 

[soulsea]

I believe that is correct ... the only issue with aftermarket navs is with the inability to use the on star ceiling microphone for the bluetooth, well you can but you'll lose it for on star. Meaning that you have to pic which one you can use the mic for because apparently you can't use it for both.

There might be some hardware workaround for this that I am not aware of.

 

[Kolt-46]

Metra makes a module to retain On Star and chimes.

Here are a couple models. You'll have to find the one that fits your options.
http://www.metraonline.com/part/GMOS-LAN-012
http://www.metraonline.com/part/GMOS-LAN-01