2006 sierra with altenator whining in speakers

[bigjohnson]

my 2006 sierra 1500 slt with bose system has developed an altenator whine coming through the speakers also seems to be started when the vehicle warning system turns on ie.. buckle seatbelts or door chime buzzers thingy... i have checked the ground to the chassis from engine and from battery also had a gm mechanic actually ground the radio housing to the chassis and had no luck.. i am wondering if its in the factory amp or radio but dont wanna have to just start buying parts without being certain what it is... BTW.. it is defineitley an altenator whine that increases and decreases with engine rpm.. also does the same thing with 2 different altenators.. any help is much appreciated

 

[98trck]

it could be a bad spark plug wire
I have had that happen, check plug wire routing but I think it is coil on plug system in your truck,so maybe a plug wire is loose at the coil or plug, check them....
I have seen plug wire spark to the valve cover in the dark before, that was crazy

 

[bigjohnson]

thanks for the advice , but this noise was there before and after the tune up.. i have checked all the grounds under the hood and chassis , also grounded the chassis to the radio housing and had no luck there either.. i am guessing it either in the factory amplifier or the stereo deck ( factory bose ) .. but hate to just throw parts at it without knowing for sure..