Alternator/ignition whine on AM radio band
 

Non-Pontiac, 95 Silverado with original AM-FM cassette. Son borrows truck, alternator blows apart, he replaces with one from auto parts chain store.

I'm traveling more with the truck, so often looking for something to listen to in unfamiliar cities.

I get an RPM related staticky whine that may also include distributor noise.

I also get horrendous noise while passing semi-trucks.

I'm curious if the alternator or the radio or harnesses are missing some kind of an RF filter.

Anybody here have experience and knowledge about how to correct?

First thing is to check that everything is grounded well. Alternator housing, engine to frame, engine to firewall, radio to firewall metal, battery neg to engine etc. Antenna coaxial cable needs to be intact so the cable outer sheath connects well to the radio metal chassis.

George

88-98 Silverado's are notorious for bad grounds, mostly due to corrosion. I own 3 of them and have had weird electrical problems from corroded body, and frame ground points.

Some alternators had a capacitator/condenser on them for radio noise, wondering if cheap reman eliminated it, and that caused radio noise? I actually don't recall one on my 93 though, when I changed it.

Thank you, gentlemen.