its, in the factory maintenance manual, and the wiring diagram might list it as an anti-diesel the manual jets into the nuts and bolts of what does what ,when ,how and why, after 1975 when the government got more increasingly worried about your being able to breath fresh air and not have you driving a horse and buggy again their ever changing emissions controls ,
their are so many vacuum temp switches and lines its why most of the problems we run across are in part due to failed parts ,vacuum leaks electrical wiring problems in these rigs, my cherokee (big MINION Hauler) i spent over 200 hours gutting 80% of the emissions equipt. , repairing chaffed wires, repinning connections, removing wiring that supported bogus E PARTS, a lot if which are no longer available, the most notable are the AMC adapted motocrap ignition system , the fomoco carb 2100 series, and the elecrto mechanical/pneumatic cruise control, having replaced them with holly hyperspark ign, sniper EFI , and rostra cruise control, and nor pass emissions check with flying colors and i can actually see and work on the motor, and not worry about reliability, and being stranded , ive spent 4.5 years completely doing a mechanicals ground up on this truck and have run into just about every issue and problem associated on fsj's , i have a very solid understanding these trucks anyhow thats my take on ramblin on.