Jeep grand cherokee 2015 Owner's Manual page 616

614 MAINTAINING YOUR VEHICLE
When inspecting accessory drive belts, small cracks that
run across ribbed surface of belt from rib to rib, are
considered normal. These are not a reason to replace belt.
However, cracks running along a rib (not across) are not
normal. Any belt with cracks running along a rib must be
replaced. Also have the belt replaced if it has excessive
wear, frayed cords or severe glazing.
Accessory Belt (Serpentine Belt)
Conditions that would require replacement:
• Rib chunking (one or more ribs has separated from belt
body)
• Rib or belt wear
• Longitudinal belt cracking (cracks between two ribs)
• Belt slips
• "Groove jumping (belt does not maintain correct
position on pulley)
• Belt broken (note: identify and correct problem before
new belt is installed)
• Noise (objectionable squeal, squeak, or rumble is
heard or felt while drive belt is in operation)
Some conditions can be caused by a faulty component
such as a belt pulley. Belt pulleys should be carefully
inspected for damage and proper alignment.