2020 SLT brake pedal vibration & AC noise HELP

[Sierra20-20]

Spanking new 2020 SLT. At low and higher speed. When I feather the brake pedal, coming to a slow/stop, I can feel the pedal quickly vibrating on my foot. It’s only happened a few times in the last week or so and it’s very hard to recreate. When I can get it to do it, if I hold it steady on that sweet spot where it started, it’ll vibrate for a few seconds but as soon as pressure let’s off or goes harder, it goes away and I can get it to do it again immediately after. It’s strange. And I also have a noisy AC compressor. It’s like a whirling sound. If the fan is on and compressor is off, I don’t hear it. Then the compressor kicks on and it’s whirling again. I’ve got into two same trucks. 1 did the same, 1 was much quieter and hardly noticeable at all. I’ve messed with the vents, speeds, everything but it’s only when the compressor is on. Maybe GMC newer trucks make this sound and it’s a design issue ? I don’t know, it’s my first GmC truck. Nice truck but wtf over. I have an appointment in a couple weeks but still. Any ideas where they could start ? 
 

update: went for a drive around town. I can feel the vibration / hear is chattering slowing from 40 mph to around 35. Barely any pressure on the brake pedal. Will chatter in the sweet spot for a few seconds. If steady pressure is put coming from any speed or 40, no issue and no chatter.. I don’t freaking get it. 

Edited June 25, 2020 by Sierra20-20

[Crow0722]

On 6/24/2020 at 7:07 PM, Sierra20-20 said:

Spanking new 2020 SLT. At low and higher speed. When I feather the brake pedal, coming to a slow/stop, I can feel the pedal quickly vibrating on my foot. It’s only happened a few times in the last week or so and it’s very hard to recreate. When I can get it to do it, if I hold it steady on that sweet spot where it started, it’ll vibrate for a few seconds but as soon as pressure let’s off or goes harder, it goes away and I can get it to do it again immediately after. It’s strange. And I also have a noisy AC compressor. It’s like a whirling sound. If the fan is on and compressor is off, I don’t hear it. Then the compressor kicks on and it’s whirling again. I’ve got into two same trucks. 1 did the same, 1 was much quieter and hardly noticeable at all. I’ve messed with the vents, speeds, everything but it’s only when the compressor is on. Maybe GMC newer trucks make this sound and it’s a design issue ? I don’t know, it’s my first GmC truck. Nice truck but wtf over. I have an appointment in a couple weeks but still. Any ideas where they could start ? 
 

update: went for a drive around town. I can feel the vibration / hear is chattering slowing from 40 mph to around 35. Barely any pressure on the brake pedal. Will chatter in the sweet spot for a few seconds. If steady pressure is put coming from any speed or 40, no issue and no chatter.. I don’t freaking get it. 

 

[Crow0722]

My 2020 Sierra does the same thing and the dealer can’t figure it out ... and recently I saw the traction control light come on when it does it every once in a while

[ChacAT4]

I’m pretty sure there is recall about that. I purchased a 2019 Silverado RST. It had so many problems and recalls I ended up trading it in for a 2020 Sierra AT4.  I did a lot of research about the GMs new T1 platform and the infotainment 3 system. Which included reading all the complaints, recalls, GM technical bulletins between engineers and the technicians. Some of the earlier 2020 model trucks still needs the recalls done. 

[Smokey Chevy]

I too have this problem with the brake pedal on my 2020 Chevy Silverado Custom. I mentioned it to my dealership’s service department after noticing it occurring intermittently. They did a ride along with me, and of course it didn’t happen, but he did ask me some questions that made me start better observing conditions present when it happens. Today, I figured out that it happened only when I applied VERY LIGHT pressure to the brake pedal when traveling between 30 and 40 mph. It would be a condition much like someone barely riding their brakes. Feels similar to how ABS acts sometimes on a gravel road. I can duplicate the condition fairly easily now. Not every time, but most of the time. I can also hear it, so I’ll probably be able to get video of it while it’s happening. 

[Thejet07]

If you ever figure this out please let me know. I’ve had this issue for 29k out of 30k miles and my dealership is useless. I have a 2019 rst with 5.3 for reference.


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