Buzzing Sound

nlindste · June 30, 2011

I have a 2009 Sierra that has recently developed a buzzing noise coming from the passenger side of the truck. The noise happens at 40 mph when I let my foot off the accelerator. The same noise happens between 70-75mph. The noise sounds like plastic buzzing or vibrating against plastic. I had removed my bug shield with no relief from the sound. My truck unfortunately is out of warranty.

Thanks

Nick

jdubub · June 30, 2011

it could possibly be your windshield trim piece . its been known to affect a number of us on here. Mine slapped on the passenger side up high, I took it to the dealer, they pulled it off, re-sealed everything and sent me on my way. its been fixed ever since. mine sounded more like plastic SLAMMING more plastic, annoying as hell......

nlindste · June 30, 2011

it could possibly be your windshield trim piece . its been known to affect a number of us on here. Mine slapped on the passenger side up high, I took it to the dealer, they pulled it off, re-sealed everything and sent me on my way. its been fixed ever since. mine sounded more like plastic SLAMMING more plastic, annoying as hell......

I will have to take a look. I had the trim piece making the noise like someone was throwing sand at the window. This noise is getting to be really annoying because it only happens in the speeds I am mostly in. It is weird that as soon as I get up to 45 it goes away and doesn't come back until 70 and then goes away at 75.

jdubub · June 30, 2011

I bet that is it

matt3 · June 30, 2011

My 08 Sierra had AC lines that were vibrating in that area.

nlindste · June 30, 2011

My 08 Sierra had AC lines that were vibrating in that area.

Matt

What did you do to solve the AC lines vibrating?

Nick

kdixer · June 30, 2011

I had an 02 Avalanche that did something very similar. There was a definite "buzzing" sound under very specific conditions. The throttle position, engine load and rpm had to be just right for it to make the noise. But as you problem, it mostly occured around the speeds I mostly traveled with the engine lugging slightly. The sound was not a rattle. It was a definite buzzing sound. It turned out to be the heat exchanger in the AC unit making contact with the plastic housing. My solution was to put a wedge between the metal cross member in the dash and the plastic housing that held the heater coil and heat exchanger. The way I found the source of the noise was to let a friend drive the truck and listen for the noise and push on certain items until the noise would stop.