It's How You Play the Game - S4-E19
Character mistake: On scene at the vehicle accident, John palpates a pulse on the driver's leg and tells Roy that he's got a good strong foot pulse. Then when Roy's on the line with Rampart we hear him say, "He has a strong fetal pulse," but presumably Roy certainly must have meant to say, "strong pedal pulse."
Answer: I believe you are speaking of the old man, Mr. Wilson. He's played by J. Pat O'Malley.
Bishop73
Correct, it was J. Pat O'Malley...he also played the grandfather with his grandson when their rocket exploded, and also played "Old Bill" in the episode with Ann Prentiss, where Gage saves the little girl from the burning tree house, and her mother falls in love with him.