I am in need of some help. I have a 03 H2. I have a aftermarket radio in my vehicle. The factory Bose amp went out so I had it repaired instead of replacing everything in the vehicle. After repairing the amp, I now have engine noise coming out of the speakers. A local shop troubleshot the issue and after they regrounded everything the issue still persisted and they narrowed the issue down to the PAC OS-2 adapter and replaced it with the Metra GMOS-04. The engine noise is not as bad but it is still there. We reinstalled the factory radio and no engine noise can be heard. Can anyone give me any clue to what could be causing this issue?