The Jeep Grand Cherokee relies on a well-lubricated transfer case for its four-wheel-drive function. The transfer case bolts on the back of the transmission. You should check its lubricating fluid every 30,000 miles and change it every 60,000 miles, more if you use it often for towing or do a lot of four-wheel driving.
Elevate the Jeep Grand Cherokee with a jack or tire ramps, if you're unable to crawl under it. If you're using a jack, make sure the SUV is secure on jack stands before working under it. Some Jeeps may be high enough off the ground that you can comfortably get underneath it, thus you can skip jacking it up.
Locate the "fill" plug on the rear of the transfer case under the drive shaft. Unscrew the fill plug with an 10mm hex wrench or 1 1/8 hex socket wrench, depending on your transfer case.
Use your finger to check if the fluid is below the bottom of the fill hole. If it is, you need to add fluid.
Drain the fluid, instead of refilling it, if it's been more than 60,000 miles since it was last changed in your Jeep Grand Cherokee. Place a drain pan under the transfer case "drain" plug before removing the plug with the socket wrench.
Replace the drain plug after the fluid has completely drained or the flow has slowed to a trickle into the drain pan. Tighten the drain plug with 15 to 25 foot pounds torque.
Refill the transfer case through the fill opening with Mopar ATF+4 automatic transmission fluid, if you have an NV 140 single-speed transfer case, or Mopar NV 247/245 Transfer Case Lubricant, if you have an NV 245 two-speed transfer case. An ID tag on the back of the transfer case will identify which type you have. A funnel or pump will help get the fluid in the fill hole.
Put the fill plug back in, tightening it with 15 to 25 foot pounds torque after the transfer case is full. The transfer case is full when fluid spills back out of the fill opening.
When changing the transfer case fluid, remove the fill plug before removing the drain plug. If the fill plug is stuck, the transfer case will still have its lubricant. Dispose of transfer case fluid at the same place you would dispose of regular engine oil.
Transfer case fluid is lighter than engine oil, and therefore, flows quicker. Be ready for it to gush out when you remove the drain plug.