I have a 1995 Isuzu NPR Turbo Diesel.... just got it a month or so ago, have not put it on the road for work yet as I have been getting a few things sorted out. It has gotten pretty cold, I have no experience with Diesels or Isuzus. Can you identify what these are and what they do? I am assuming it is a "choke" from the pictue on the knob but really do not know. Please let me know.