I have a 99 Ranger 4.0 xlt and until recently the 4 wheel drive worked OK. But the other day when I went to engage the 4 wheel it would not engage. I have checked the vacuum lines to the hubs and even replaced some of the lines but no luck. Several years ago I installed Rugged Ridge lockouts and they have worked fine up until now. I checked the fuse to the vacuum hubs and it is OK but is there something I have failed to check? What puzzles me is one day it was working and the next day it wasn't. Any suggestions or ideas. Thanks

 

If you replaced the vacuum hubs(PVH) with manual hubs then the vacuum lines to the front axle don't do anything anymore
If either manual hub is not Locked then no 4WD, front is an OPEN differential

Do the 4WD lights on the dash come on in 4high or 4low?
If so then transfer case is shifting into 4WD
If not then its not shifting into 4WD, tap shift motor on the back of the transfer case with a hammer/wrench, and see if it shifts

 

As far as the vacuum lines not doing anything that was my understanding also but I checked them anyways. The 4 wheel high light comes on and you can hear a click when you move the switch back and forth. I have not checked the hubs to see if one might not be engaged but I will after lunch.

 

I went out and checked the hubs and both were locked in but when I took the hub cap off the right side the hub almost fell off the CV axle. I took the wheel off and I could see the retainer snap ring had came out of the groove on the CV transaxle and worked forward. About two months ago I had replaced the complete transaxle and apparently the snap ring had not completely seated in the groove and let the transaxle disengage from the hub causing the 4x4 not to work. I cleaned the axle up and reinstalled everything making sure it was where it was supposed to be and checked it out to make sure it worked and it did. Thanks again for the input.