I guess I haven’t updated this in quite a while — mostly because the Ram has been nearly trouble-free.
By the Book found a tiny hole in two wires (one of which was the J1850 bus) in the loom adjacent to the transfer case. I had actually had that apart months ago, but I was working on the connectors themselves and didn’t inspect the loom. The mechanic said a ground strap had worn a tiny hole in the loom over 200k miles.
He wrapped it in some new plastic loom, so it shouldn’t be a problem again soon.
$300 well spent. I wish I had taken it there a year ago.