I enjoyed a video of a grid heater delete yesterday. AFter 70k miles the intake side of the grid heater looked like the firebox on a steam locomotive that has gone too long between cleanings. Really ugly. Not liking that.
I wonder if that's what the 600 hr thing is about. Wonder if it does some sort of cleaning cycle by then where the heater is on long enough to burn off any carbon deposits. (and the rest of your engine bay, if the relay fails then.)
I just joined over this issue, seems a clear case of adopting new technology before it's proven. I'll be taking my truck to the dealer, but will be swapping to a mechanical relay afterwards.
My guess is the fact that the intake heater "cycles" when ambient temps are low means they were either starting to have issues with the mechanical relay wearing out, or were concerned about that. Only get so many cycles out of a mechanical relay, and increased number of cycles between failures are a big reason why SSR's are a thing. That being said, swapping out the mechanical relay is easy given it's location in the engine bay, and immensely preferable to a fire.
Ram should just abandon the SSR till they've worked out the kinks, and a return to the mechanical relay should be the fix. I know I can't trust their SSR designs anymore, two separate issues in a year? That's a sign.