Cab Noise Gmt900

longhorn_giant · December 16, 2008

I've been noticing a buzzing/vibration sound coming from somewhere the glove boxes on the passenger side. I've tried to find a trend as to when it happens and I haven't been able to. It happens when the A/C and/or heater is not on- my first thought was it was the blower fan. I seem to notice it more when I'm slowing down from highway speed. It'll buzz for about 3 seconds or so. I'd describe the sound as very similar to the sound the transmission of my mom's old 91 dodge caravan made when it was downshifting coming to a stop.

Could it still be the blower fan, even when the unit is off? I know it's still pushing some air through the vents when it's off - I can feel the cold/warm air just coming through.

I've also got a buzzing sound in my door panel on the driver's side, but I can easily fix that. The truck's under warranty still too so I can take it in and have them look at it, but I'd like to know what to tell them other than, "It makes this noise sometimes."

Zembonez · December 16, 2008

I've been noticing a buzzing/vibration sound coming from somewhere the glove boxes on the passenger side. I've tried to find a trend as to when it happens and I haven't been able to. It happens when the A/C and/or heater is not on- my first thought was it was the blower fan. I seem to notice it more when I'm slowing down from highway speed. It'll buzz for about 3 seconds or so. I'd describe the sound as very similar to the sound the transmission of my mom's old 91 dodge caravan made when it was downshifting coming to a stop.

Could it still be the blower fan, even when the unit is off? I know it's still pushing some air through the vents when it's off - I can feel the cold/warm air just coming through.

I've also got a buzzing sound in my door panel on the driver's side, but I can easily fix that. The truck's under warranty still too so I can take it in and have them look at it, but I'd like to know what to tell them other than, "It makes this noise sometimes."

The blower fan is never off if it's anything like older trucks. They ran on a low speed even when off was selected for ventilation. Maybe someone that is a tech can chime in here.

OhOneW6 · December 17, 2008

Does this sound familiar? Here is a link to the TSB

http://www.gm-trucks.com/forums/index.php?...ticle&id=22

tobias · December 17, 2008

I have this same noise. I'll check out the issues mentioned in the TSB tomorrow. (We're having a bit of ice right now so I am staying in.)

There has also been a member who found his engine cover was vibrating against a few things in the engine bay. Try removing it and riding aruond without it. If the noise is gone, we know the problem. If not, time to move on to the next suspect.

longhorn_giant · December 17, 2008

The TSB sounds like it might address it. I'll look into the fender cover tonight. That could be it since I ended up taking those off when I was working underneath awhile back. I know it's coming from the right side, so I don't think it's the engine cover, but I'll make sure that's clear too. Thanks for the TSB

shocktrp · December 17, 2008

I have that problem on my 2500. At first I thought it was stuff in the glovebox, but now it sounds more like it is under the hood. Happens mostly when accelerating from a stop while turning left.

I'm glad someone else figured out the problem - it looks like the TSB covers it.

chittyg · February 20, 2009

I had a similar noise on my 08...dealer tried several things...turned the transmission dipstick 180 in tube...supposedly bumping firewall...relocated a wire to the alternator supposedly hitting the firewall...added insulation to the ac-vent ducts near the radio...finally found a wire bumping the the back of passenger airbag somehow...rerouted somehow and added insulation indicated on paperwork...this took care of the noise in my dash...still way too much road noise in the cab.

Trav_13 · February 20, 2009

I had a similar noise on my 08...dealer tried several things...turned the transmission dipstick 180 in tube...supposedly bumping firewall...relocated a wire to the alternator supposedly hitting the firewall...added insulation to the ac-vent ducts near the radio...finally found a wire bumping the the back of passenger airbag somehow...rerouted somehow and added insulation indicated on paperwork...this took care of the noise in my dash...still way too much road noise in the cab.

If any of you have the Auto A/C like I do...it could be what is called the Aspirator which is that little fan in the headliner, right above your head....I though I had a noise coming from the Firewall area that lasted only for a few seconds at a time, and it ended up being that part up there...just a thought!

VMax2007 · February 20, 2009

If any of you have the Auto A/C like I do...it could be what is called the Aspirator which is that little fan in the headliner, right above your head....I though I had a noise coming from the Firewall area that lasted only for a few seconds at a time, and it ended up being that part up there...just a thought!

I had the HVAC Aspirator noise too. But how the hell could you mistake a noise that is literally a few inches above your head for a noise in the firewall area???