Jeep Cherokee 4x4 won't engage

pjs412pjs412 Member Posts: 2
edited June 2014 in Jeep
I have an 89 Cherokee and the 4-wheel drive will not engage. Any thoughts on where I might start?


  • rhtransrhtrans Member Posts: 84
    If you have a "manually" shifted 4wd, when shifting to 4wd, a vacuum switch on top of the transfer case switches vacuum paths to an actuator on the front differential which has two vacuum lines running to it. One line keeps it disengaged when vacuum is applied to it as the other engages the front end when vacuum is applied to it. You first need to make sure the transfer case is engaging & turning the front drive shaft when in 4wd, if not then somethin is wrong in the transfer case but if so then the front end is not engaging. Just make sure you have good vacuum (above 15 pounds) at the actuator. If no vacuum, check the vacuum at the 4way switch on the transfer case. The vacuum is supplied from a line running from the engine. If there is vacuum at the actuator, make sure it's switching back and forth when shifting 2wd to 4wd. If it's not switching then the vacuum switch is bad. If it is switching then something is wrong with the actuator or the fork and slider in the differential. Hope that helped.
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