4wd Light On

Just Bought A 2002 Durango 4x4 The 4wd Service Light Comes On After 30-45 Min. Of Driving What Is The Cause Of This Problem. Took Back To Dealer Did Not Find Anything Wrong, Light Still Comes On After Driving Long Periods.

Messed up sensor I guess.

I have similar problem when it rains and i was told its a loose ground wire some where.When it gets wrsam i'm going to check it out