Hello all, I am having an annoying buzzing noise being picked up through the antenna in my 98 Blazer 4WD that occurs when the key is turned on and/or the engine is running, and I'd like to find where it's coming from. It doesn't vary in pitch with engine speed like an alternator whine or ignition noise would, and it only affects the FM. AM is not affected. I have had this exact same buzzing occur in a 91 Corsica with the 2.2 throttle body injection, an 86 Camaro with a mult-port injection v6, and a 93 GMC Sonoma that has injection similar to my Blazer's 4.3 Vortec V6. I have tried checking the grounding of my antenna, grounding the chassis of my ECU/Computer to the chassis of the vehicle (if the ECU is where the noise is coming from), installing ferrite beads on the leads coming from the ECU, using noise filters on the power and antenna of my radio, using different radios (both stock and aftermarket), and nothing seems to work. I also get this noise with any portable FM radio near the vehicle. The interference occurs all over the FM dial.

To give you guys an idea of the noise I am talking about, I have included an MP3 where I recorded the noise in the attachment. Have you had this noise before in any of your rigs? Where is it coming from?

 

some ignition systems have a condenser installed to absorb rfi. are the spark plug wires radio suppression wires.

goggle spark plug wires and radio suppression. It may have a solution.

 

Thank you for your reply. Yes, I do have radio suppression wires. Do you know where the condenser would be installed in a Blazer, just to rule that out? This interference happens without the engine running as well. It sounds like an electronic component such as an ignition computer doing it.