1989comanche Rock Crawler Posts: 689 Joined: Jul 13, 2014 Logged 1989 Comanche P/U Does anyone know what color vaccum line is supposed to do what on a 89 MJ. There are 4 tubes if my studying is right one is the vacuum source one vent line and one for engage axle one for disengage. I think I have a broken line somewhere. I have checked the actuator on the axle it is cycling correctly. If I apply vaccum to the right ports it engages and disengages the collar to lock the axle. The transfer case shifter does engage the front driveshaft.