I have a 91 Cherokee that the 4x4 will not engage..I suspect the vac swithch but not sure..the lines appear to be ok...is there a way to test the switch???

 

The lines are attached to the diaphragm on the axle? on my 90 once the fork the diaphragm works, broke. You can check the switch just by checking for vacumme at the diaphragm. By the by, My (actuator?) has a port deal that sends vacuume back out to a light switch when it actually has moved the fork. So with my broken fork, the 4wd light came on the dash when the sleeve had NOT actually slid onto the splines. My lines fall off allot. Good luck! D.

 

does shift lever feel like its moving thru the gears and actually trying to engage? (first time it went out) my rommies wrangler suddenly wouldnt shift outta 4 (low) and the shifter lever was just sliding along w/o any real resistance. so i crawled under and there is a little T shaped bracket whos post had come unseated from it pivit point and was just moving freely. i had her slowly move lever till pin was inline with the hole and all was well again!

 

X2 on checking the linkage...

 

i shoulda messed with my roomie and told her it was bad news bears... its a 97 and she got it for an ok price, but it then went right to shop... which tallied 1600 bucks... so i didnt wanna make her cry...