This one should be kind of easy...
I think it was one of those "made for TV" movies. Anyway, this black guy who plays football and it also a speech therapy major takes a volunteer position with a young kid who's got various physical disabilities (I think he's in a wheelchair) and, of course, has speech problems (maybe do to a muscle condition?) Among other things, the guy helps the boy by organizing various fundraisers, including a car wash, to get the kid a new computer.
Later in the show the guy gets sick, ends up getting cancer (or something) and passes away. The movie ends with him talking on the phone with the boy, and, upon hanging up, the kid's mom asks what the guy said. Kid looks at her and, with tears in his eyes, tell hers, "He told me good-bye."
This would have been probably mid nineties, late eighties at earliest.