chirping noise

[todd308]

Just as an update I can verify that on my 21' if you drive in L9, it will not do the chirping at low speed downshifts.  L9 disables DFM and autostop from my understanding so it would appear related at least in some way to those things being engaged.   

[Sqrls]

I believe the starter on this generation of trucks isn’t a traditional toothed starter that spins the flywheel, but rather spins the drive belt in the front to start the engine. The belt on these trucks also does not have a tensioner. So if the starter has a clutch like an ac compressor to engage the drive belt, that would create a chirping noise if the clutch material made contact or had a piece of debris in there. Would also explain the sound happening during slowdown or downshifting. 

[todd308]

Yeah it sounds like at least one dealer is replacing the stator shaft assembly and transmission oil pump in an effort to fix this for another user on facebook.  It sounds like they've done that on other vehicles and it's helped the issue.   I'll report back what the result is. 

 

I think my scepticism that they can fix this is simply due to the fact that it's been happening on 3 years of trucks now, so it's clearly a pervasive issue whatever the cause, but it's certainly not just a bad batch of parts.  So even if they replace the parts, if the new parts have not been updated (which seems unlikely since we're still seeing new build 21's with this problem) it seems like those replacement parts would just do the same thing.  

 

I will say though it sure is embarrassing to drive a truck that sounds like it came from a scrap yard every time it starts or downshifts.   I also have to say that while the Ford's, and Ram's I've had also had issues, it seemed like dealers were more willing to fix them, with GM it seems like they just find excuses to call issues "normal operation" or train techs to say "I can't hear that squeaking/chirping noise when the truck starts up......meanwhile I've seen people stopped next to me with open windows in traffic look at my truck like "That doesn't sound good!" when it restarts. 

[Kbeck]

I am having the exact same problem with my truck. It started at around 3000 miles, I told the dealership, brought it in and they said they could not duplicate the sound. So I took videos of it and emailed them. They are saying the same thing, that it is normal. That is not an ok answer in my book. You pay 100k for a truck and expect everything to work right. I’m thinking on contacting my extended warranty and have them check it out. Pretty sad that GMC is trying to say this is normal.