Alright I have a 98 Expy and it has the 2H, AWD, 4H, and 4L. I was having problems with it in Awd it would last about a block and then would start flashing. It would stay in 4H but would have to stop to shift it in, couldnt shift on the fly. And 4 L worked fine. Researched on here and they say motor bad or clean the magnetic sensors. So I took off the transfercase motor and it is working properly, cleaned the sensors and re-installed. Now it stays in AWD and 4H great. Will not even shift into 4L now. And again with both settings you have to bring the truck to a complete stop before it will shift into anything.

Any suggestions?

 

Since you didn't mention it I figured I'll ask...you are shifting into neutral before attempting to switch into 4WDL correct?

 

Yes. Shifting to low is front neutral. Just really weird. I am wondering if the motor is working, just not strong enough to shift on the fly or what. Very confusing.

 

The shift motor only controls the mechanical high to low (and back) shifting within the transfer case. On the fly engagement is accomplished electrically by engaging the front clutch in the transfer case.

 

So this is a electrical component that needs changed? Or these is something wrong in the transfercase internally that is bad? Truck has 165,000 miles on it. I am still confused as to why I have lost 4L.

 

I think your transfer case is fine. Since you were able to shift into low before removing the shift motor and now you can't after reinstalling it, then it would seem to me that the shift motor is either flaky or it didn't go back in correctly.