My 2020 Sierra Denali 3500 has had a rhythmic knock or loud tick when decelerating since new. It now has about 7K miles. It seems to be louder as the truck gets hot, especially when towing my RV. I'm not good at determining the direction of a sound, so I don't know if it is engine or trans. I've read the thread on this forum about the knock at idle, but this sound is not heard when stopped at idle, only when taking foot off the accelerator pedal to decelerate or going downhill....not braking.
I took the truck in at about 500 miles to get interior warranty work done and told them about the noise. They just said "could not duplicate". When I took it in to a different dealer for the first oil change at about 6k, I told them about it. They did not even try to duplicate the noise. The service rep said that GM says the noise I described is coming from the DEF pump and is normal. My friend has the same truck (except 2500) with about the same miles. His has never heard this noise.
Anyone aware of this noise and/or another forum thread discussing it?