Pull out the fill plug, the level of the fluid should be up to the fill hole.
Check the level of the lube in the differential. Also could be tire noise.AnswerI work at a car dealership and have had driven many Grand Cherokees. The noise may be coming from the spider gears in the rear diff. It is common. AnswerRear axle bearing failures are very common in those Grand Cherokees. ANSWER:you should try just replacing the whole rear end, i heard it's cheaper, i have a grand Cherokee Laredo 97', that has a hoovering sound, and a machanic i know said it's the teeth in the middle of the rear axle (the big ball part in the middle) and it's like surgery, plus it's just plain cheaper to replace it all
First check the level of the lube in the rear differential. If it is low add the correct weight lube. If not, then you have worn gears. Also check your rear wheel bearings as that is what you may be hearing.
maybe
The speed sensor ring is in the differential case in front of the ring gear. To get to the unit you will need to remove the differential cover and drain the lube which requires replacement along with the cover gasket. Check to find out what lube you need to use and if synthetic is required. If you are not familiar with differential or transmission work you may want to get an estimate from a transmission shop or your mechanic.
75 80 90 gear lube is fine
Usually you fill it to the bottom of the hole.
75W-90 synthetic gear oil
85W90 gear oil and add a bottle of positive trac. lube also.
I would suspect a defective universal joint on the driveshaft. Can also be a bad wheel bearing or axle bearing. And lastly, a problem with the rear differential. Check the gear lube level in the differential first.
Noises like grinding. Low power to the wheels when you accelerate. Noticeable leakage from the seal of the differential. Most of the time it just needs lube.
3 quarts per axle
80w90 The 2004 Rubicon rear differential uses 75W140 synthetic oil. On each side of the differential cover plate is a tag listing specific numbers for the differential. One of the tags lists the lubricant installed by the manufacturer. I also have a 2004 Rubicon and the rear differential on mine uses 75W140 synthetic oil plus 4 oz of limited slip lube. The front differential lists only 80W90 oil with no limited slip lube.