2000 Jimmy 4wd

I have a 2000 Jimmy with approx. 70k miles. I recently went on a trip to the Grand Tetons and wanted to do a little off-roading. I started to go up a hill and when I hit the 4x4 Hi button, the light lit up, but I don't believe the front wheels were engaged. Since there was no one around, I stopped, went back to 2 Hi and then pushed 4 Hi again. The light lit up but when I hit the gas to continue up the hill, the rear tires were turning and not the front. I went to 4 LO, same story there. Could anyone help with this? I read about disconnecting the neg. on the battery to reset the computer, would that help this issue? Thanks for any help.

the front diff actuator is powered by vacuum. i saw one where the hose was pinched by the batery and another where the hose poped off the reservior(in left fender) try removing the acuator and shifting into 4wd if the actuator moves the problem is elsewhere. does the front driveshaft turn?

the front diff actuator is powered by vacuum. i saw one where the hose was pinched by the batery and another where the hose poped off the reservior(in left fender) try removing the acuator and shifting into 4wd if the actuator moves the problem is elsewhere. does the front driveshaft turn?


I don't believe the front driveshaft turns, I know that no power is going to my front wheels.

hey

I'm in the same boat. 2000 Jimmy with 69K and no 4wd. I disconnected the negative battery terminal but this made no difference. I pulled of the passenger side kick panel and can hear the control module click when I hit the Auto 4wd or 4 hi switch. The light blinks yellow like normal but never turns green. It just goes back to 2 hi after about 30 seconds. When it was working properly, the light turns green after about 5 seconds when the 4wd engages. Any I dea what to try next? Is the 2000 with Auto 4wd operated by vacuum?