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***UPDATE*** Engine tick was diagnosed as potential wrist pin or retaining clip failure. Severe scoring found on wall of cylinder number two. Engine is being replaced and should be up and running by the middle of next week. The rattle was diagnosed as torque converter engagement at low vehicle speed, lock-up with DFM engaged. About 5th gear. They have another 2024, 5.3/10-speed (4,000 miles) that rattles in the same fashion. They’re thinking a software update to disable DFM at low speeds would be a likely fix (does not do it when all 8 cylinders are engaged). Further info will be provided when engine is replaced; a GM engineer is going to pay the dealer a visit for my truck to see if adjustments to the programming is necessary. ***uploaded this linked video for TCC sound*** Truck has 570 miles on it. It’s a 2024, 5.3, MHT 10 speed, crew cab short bed work truck. The other day, I was coasting (between 15 and 25 mph) and heard this loud, repetitive metal knock or tap sound under very light throttle. Sounded like it was coming from the engine bay, through the floor, approximately center or slightly to the right from driver seat POV. It came and went when I was very lightly engaging/disengaging the throttle pedal. It does not happen when I’m accelerating or when the drivetrain is under load. This morning, on start up, I hear this unusual metal “clack” that seems random in interval, but consistent nonetheless, at idle. My coworker drove beside me, and through the usual DFM noise, he heard the metal “knock” or “tap”, very loud, from the engine bay, while cruising and very light throttle. When I got to the dealer to drop it off, I couldn’t replicate any of the issues. Of course. I sent these videos to the service advisor, because he was stumped like I was.

Hey guys, I have a 2020 Silverado 3.0l Duramax. I'm looking for the gm filling procedure. I wasn't able to find it and was going to try a local dealership for it if this doesn't pan out. I know the temp needs to be brought up and gears cycled through, but I was hoping for an official document for it. If anyone has it I'd appreciate it.