07 nbs Silverado, installed Avicx910BT, onstar harness, HD Radio, XM and Ipod cord

~The volume is not as loud as factory head unit?

~My door chimes and turn signals are not working properly have checked connections their all fine, think it might be bad onstar harness, do you guys think that might be it? Using the rca cables from onstar harness

It is either a bad GMOS interface, it is hooked up incorrectly, or the GMOS MAY have a volume control dial on it that may need to be adjusted.

i just installed this unit in my 09 Malibu. I bought the GMOS-LAN04 unit to retain OnStar. Onstar still works, so that's good. But my stereo is not very loud either. All the way up is like half way on the factory stereo. i think i may need to adjust the dial on the interface box. but i thought that was just for the turn signals and onstar volume? i can hear very faint clicking when i have my turn signals on. everything works great, just not at all loud enough.

************ Ok so, there is a dial on the GMOS that adjusts the overall volume of the stereo. it also adjusts the volume of the door chime.