Engine noise through speakers

[jb817]

I have a 2000 Chevy Silverado that recently has been making a whinning noise through the speakers that corresponds with engine RPMS. I have seen this before when a stereo was poorly grounded, but this noise even happens when the radio is off. I am lost as to what could cause engine noise across speakers when the radio is off. Also, this noise is intermittent. It seems to happen when it is wet or very humid outside. The only thing that has changed on the vehicle recently is I installed a new battery. Any ideas???

[Redneck_Cadillac]

radio noise when the engine is running is generally caused by "backfeeding" by the alternator, or a bad spark plug wire, that's no longer "supressing" the spark.

the alternator has a condensor on it, to prevent this. you may have a problem with your alternator/regulator.

check your plug wires .... if they're bad (or just one) it can cause this. by putting your truck on an ignition scope, you'll see a bad plug wire right away..... especially since you say it does it intermitantly, especially when humid or raining. this is when a bad plug wire is the most obvious.........