I installed a pioneer z1 in my 09 gmc with all the proper plugs and modules and can't seem to get the onstar to work. Anyone run across this or have suggestions? Everything else works fine. The onstar responds when you hit the button but no sound, the dash light only comes on.

I had the same problems in a 07 I think it was. Never did figure it out. I tried three different modules at the time as well. Let me know if you figure anything out. I would ask over at the other site I told you about, might get more answers there.

What interface are u using for the onstar?

I found the problem, I should have used the Peripheral GMAHL1. It is specifically for the 09, It incorporates the factory Onstar, Chimes, Bluetooth , factory XM module and even the IR headphones..