I was test driveing a 99 gc 4.7 and we had to go up a small hill but the back tires were spinning so I hade to put it in 4 low? shouldent it have kicked in by its self?

Other forums said that it most likely a gerotor pump I dont want to buy a new jeep and have to put a transfur case in it....how can I go about testing it to make sure its not shot?

 

For reference: http://www.wjjeeps.com/tcases.htm

We bought an '04 WJ w/4.7L new w/88,000 miles now, and we've never experienced the symptoms you describe. The rear tires will spin briefly before the fronts grab, but I've never had to engage 4-Lo to get the fronts to engage. I suspect there is t-case problems with the vehicle you're describing.
Dan