I'm glad that it's quieter since adding coolant.
A few questions:
1. How did you determine if you were low on the coolant?
2. Is this something that needs to be done at the Tesla SC?
3. Is the humming noise notably quieter and how frequent / when do you notice it coming on?
If replacing the pump fixes the humming in other other Y's, i'm assuming that the coolant has to be replaced or filled as well as part of that process.