Just to be clear, you feel a vibration when the vehicle is coasting but it immediately goes away if you step on the brake? If so, I suspect this is the torque converter clutch that is doing this. I would start with checking the fluid and then adding what is called a friction modifier to the transmission. This basically is a fluid conditioner that is meant to "soften" the clutch material so that it slips easier and doesn't chatter which is what is most likely causing the vibration. This video shows how to replace the torque converter
I attached a picture of what this looks like. It is just a 4 ounce bottle that you pour directly into the transmission. It is actually made for rear ends so that when you replace the new clutches in the rear, they don't chatter.
This has worked on many different vehicles but I would only add one bottle. Too much and the clutches can get prematurely fail.
Lastly, just to try and confirm this, can you press the tow/haul button and see if it still does it? This doesn't disengage the torque converter permanently but it does change the engagement points so if it changes this issue then we know we are on the right path.
Wednesday, August 26th, 2020 AT 2:34 PM