89whiteXJ

Ok I have an 89 that has the 2 4H N 4L transfer case. I recently bought this jeep. When I first tried it the part time light would come on and you could tell it was turning the tires in the sand. Then yesterday we were playing around and flexing it in a ditch. Placed it in 4L b/c the rear lifted off ground and was not doing much and it rolled the jeep out, but no part time light came on. So then after that I went to a little place I like to play in the mud with my old truck and again place in 4L and again no light. Well it would not sling mud or spin. It was like being in 2wd. Whats the deal? I dont understand this part time stuff.

winston427

With that shift pattern you have the NP231 transfer case. Being a 89 you also have the vaccum disconnect front axle. Meaning the passenger side axle shaft is two pieces that is connected by a collar. There is a housing on the passenger side of the axle tube that houses the shift motor. It is operated by vaccum and they are prone to failure. It could be something as simple as a vaccum line has come off or the shift motor itself has failed. There are several options for repairing the shift motor ranging from a factory replacement (not cheap) to taking it apart and rigging it to stay locked.

89whiteXJ

but what about the fact that is worked when flexing but not mudding. with that part time this it should spin in the mud correct?

winston427

Mine is bad on my 91, I can engage my tcase and the front tires will turn for a few minutes. Then the vaccum will leak down and it will disengage and not work for quite a while. I took mine apart and rigged it so it stays locked. The part time light works off a sensor mounted on the housing. When the collar is engaged the sensor makes contact and therefore the light works. The collar may move over just enough to lock the shaft but not contact the sensor for the light. The shift motor is most likely the problem.

89whiteXJ

ok cool thanks for the info. I will check it out and see if I can figure things out.

89whiteXJ

I was wondering what you did to make it stay locked. Does it cause any problems?
Thanks