I just bought a used Ram 1500, 2019, Big Horn. When I have the truck loaded up fully with my business stuff, I get this hum or drone that lasts for about 3 seconds and then goes away for about 5. This repeats over and over. I took half the things out of the truck and the hum stopped. It seems to go away above 80 mph. It happens at all speeds below 80. It even happens on occaision when I first start the truck. It is odd that the 8 second cycle holds up despite my speed. The fact that its not a constant sound and goes ryhthmically on and off is weird.

 

Electric Power Steering?