99 Gmc Sierra 4low Not Working Only 4hi Works

[RHowington]

Ok here is the deal I hope someone can help me and save me a trip to a transmission shop.

I recently bought a 99 GMC Sierra Z-71 Push Button 4x4. I sometimes can get it to lock in 4low but the last couple of weeks you hear the acuator then you hear and feel a CLICK CLANK---CLICK Clank!! Then it goes back into the gear you had selcted before. I can get 4hi to work every time.. I have noticed the lights are going off on selctor and took off fuse panel and put my hand in dash and mesed with the wired and it makes them come on and off so I know i need a new selector but it dont explain why 4low only makes that sound. And you feel it Clank! Its almost like its trying to spin the driveshaft. But the truck is in Nutrual... Anyone with any ideas??

[JRLZ71]

Could be a transfer case sensor? Just a guess...

[ColoradoSkiCountry]

Two things. The switches on the 99-06s were known to be bad. If your lights go off I would suspect a bad switch. Get a replacement from gmpartsdirect cheapest way of doing it and you can change it yourself.

 

After the switch is changed, then try it again. You also may want to be rolling at 1-3 MPH in neutral when trying to put it into 4-LO

[RHowington]

ok now today im getting a Service 4x4 light on my gluster... Im ordering a new switch tommorrow I hope this fixes it all!!! ERRRR