Electrical
 

Has anyone had trouble with there 4wd not working what I mean is when I turn the switch it will engage the light on the dash will come on but only once and awhile not when you need it sometimes if I shut my truck off turn the switch to 4wd and start it it will work but not always I replaced the shift selonoid last year and everything was working fine but not any more

Check the vacuum pump. Might be a leak at the hubs??

There's no power going to the shift motor on the transfer case I brought to the shop today there's just to many electrical components to the 4wd I'll let you know what was wrong when its fixed