So i am familiar with alternator whine... but NOT this kind. As of today (established install), when the headunit turns on it begins whining then it gets louder, and Louder, and LOUDER like a gradual screeching, it doesnt seem as if there is an end to the pitch because i get scared and turn off the HU before reaching the KABOOM or whatever its leading up to doing... I replaced the RCA's only to have the same prob. whats the cause? and whats the cure? My non-professional diagnosis is that i need Ground Loop Isolators. PAC LNI-1? HU is a Pioneer 7100BT. Thanks guys
pull the RCAs from the ehad unit and try running the sound system with an iPod or something to see if the head unit itself is the source of the whine. If it is, then you may have a damaged ground point within the head unit (common on Pioneer units of the past for example) and you need the head unit repaired or replaced, if it's not the ground wire for the head unit that's bad (bad ground point)
If the whine is still there, (you know its not the RCAs) then the amplifier is probably damaged.
Im not sure i understand what you mean by run it with an ipod? Every speaker in the car is on an amplifier and the HU has been in the car for 6 days now. Brand New unit. Im gonna play with it some more today and re-establish the grounds as the HU is just grounded through the harness. Im going to try finding something behind it to ground to. I have had a small prob like this in the past and fixed it by grounding out the RCA's im gonna give that a shot and see where it goes. thanks glass
yeah like I said, Pioneer is notorious for bad grounds on their pre-outs. also, you should always use a chassis ground for the head unit and not use the factory harness ground. It's common for the harness ground to be crappy and usually long, and run close to ignition circuits which introduce noise.
I meant you can bypass the head unit entirely by using something like an iPod with an 1/8th inch stereo phono to twin RCA adapter cable to bypass the head unit and see if it's the source of the noise. It's a much faster alternative to swapping teh head unit, and it eliminates the wiring harnesses entirely.
I've been surprised at the number of Pioneer head units with touchy microfuses. It's far cheaper to just ground one of the RCA's to the head unit chassis than to fix the microfuse. Too bad customers don't know that when they send in their Pioneer head units and end up having to pay $$ for the repair. On the plus side, it doesn't look ghetto when fixed properly.