I have a 99 convert with the Mach 460 audio system and alpine head unit, something is causing an unbelievable interference in the rear speakers. it is a buzzing or humming sound most of the time and when the engine is running it will match the sound of the engine (rev engine same sound is piped through the speakers). other times it sounds like someone is blowing into a microphone. it is loud and obnoxious. and also it pops when i press on the brakes so any kind of electronics that are turned on make a noise through the speakers. if the radio is shut off = no more sound at all.
my only assumption is that it has to do with one of the amps but those who have this system know how wonderful it is to get to those amps..
no clue where to start and i live in a town where i dont trust anyone to touch my car..

Thanks
Geoff

 

is the deck still stock, the system has not been changed at all?

It sounds like a grounding issue I would guess, but that is always an installers first guess. Try turning the system on and then going back and giving the amps a "technical tap". This is difficult to describe online as it took me years to perfect, but just give it a couple of light "taps"(fingertips), if that doesn't do anything move up to a "thump"(Palm of hand), next try to get ahold of the wiring hrns's and give them light pull, tug, and then jiggle(sorry for the technical terms). If none of this works then you need to get your 10 lb sledge(just kidding)........... We need to try and re-create the noise and then isolate what amp it is comming from, then which hrns, then which wire, ect.......

Also check your tail lights and the wiring going to them if you notice sounds with them going on and off. Check the spots that they ground to make sure they are still tight and clean.