yesterday, i was driving my moms 03 suburban with 120k on it and i was going up a very steep dirt road and the truck lost all power to the rear wheels like it was in neutral and for some reason it went from 2hi to 4low. The engine just revved when i accelerated. When i shifted from drive to park it slammed through all of the gears. i then shut the engine off, restarted it and every thing seemed to work fine exept 4 wheel drive did not work. Since the hill i was driving on was covered in snow, and i had come to a stop, i had to slowly roll all the way to the bottom and then gather up speed to make it up the hill. when i got home 2 miles later, 4 wheel drive worked again! i dont think the truck has had any problems that i can remember before this incident. i am very confused to what could be the source of the problem. Also, when the vehicle lost power to the rear wheels, the battery light came on. Should i worry about this?
(My mom has driven the vehicle since and no problems have occured.

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sorry for making it a novel.