Jeffrey Allen

I'm calling another dealership today to give them a shot. The dealership I bought the truck from doesn't seem to interested in trying to fix anything. I will post how this trip goes.

There is a service bulletin for 2018s that changes the transmission fluid to help with a torque converter shutter. On my 19 if I put it in manual 7th it won't shutter/vibrate, I don't think it goes into DFM at that rpm on the highway.

Yeah, it happens on almost all of my drives if they involve highway. 19 LT Z71 with the 5.3 8 spd transmission and If I remember correctly a 3:21 gear ratio. I'd love to know what tells it to go back to 8 cylinders, I imagine it would be rpm. I'm wondering if something as simple as a slightly bigger set of tires would cause it to get out of DFM mode quicker and reduce the shake.

Update just heard back from the dealer. They could not replicate the vibration, which is surprising because it literally does it every drive on the highway. I'm going to give another dealership a shot. Does anyone know what the truck uses to determine when DFM should turn off?

I should also add the vibration occurs when the truck has some minor resistance like a flat or slight grade and stops once the truck down shifts or AFM shuts off

Hi everyone, my 2019 Silverado seems to have a shudder/ vibration when cruising on the highway. This happens quite often on my drive to work and back. I put the truck on manual mode and didn't allow it to get into 8th and the shudder/vibration was gone. When I took it into the dealer to have it looked at they called it normal operating but the loaner they lent me had the same issue. I came across a service bulletin for 2018 Silverado's that called out a transmission fluid change to help with a shudder issue with the torque converter. Has anyone experience these issues and tried this service bulletin or have a different fixed that worked? Any help is greatly appreciated.