Advertising For Dummies: Schneider's last job is a commercial (1986)

 One Day at a Time had ended its CBS run in 1984. Two years later, Pat Harrington brought back his character from the show, building superintendent Dwayne Schneider, to do a commercial for Trak Auto, filmed in Maryland. Check it.

I think he might've done a series of spots for Trak Auto, but this so far is the only one on YouTube.