Assuming you're talking about the caliper, it would be much easier for you to get a Chilton or Haynes manual - which tells you what to inspect and how to inspect it - than for us to try typing out an in-depth explanation here.
A wheel cylinder describes "Drum Brakes" - Drum brakes have one cylinder with two diametrically opposed pistons.
becasuse its a rear wheel drive vehicle
The grand Cherokee does have four wheel disc brakes. The wrangler and Cherokee have rear drum brakes.
Disc brakes at the top of the caliper Drum brakes at the top of the wheel cylinder
A piston on each end of the wheel cylinder pushes outward when the brakes are applied. This pushes the brake shoes against the brake drum and stops the vehicle. The pistons are forced out by the pressure of the brake fluid inside the wheel cylinder when you apply the brakes.
A piston on each end of the wheel cylinder pushes outward when the brakes are applied. This pushes the brake shoes against the brake drum and stops the vehicle. The pistons are forced out by the pressure of the brake fluid inside the wheel cylinder when you apply the brakes.
Jeep Wrangler wheel lug patterns years 1987-2006 are 5X4.5Jeep Wrangler wheel lug patterns years 2007-2014 are 5X5
First you have to jack the car up after loosening your lug nuts and then you remove the wheel. After you do this, you have to pull the brake drum off. Next, dis assemble the brakes then disconnect the brake line from the wheel cylinder. Then you remove the two bolts holding the wheel cylinder on and put the new one in. Re install the bolts, and brake line, put the brakes back on, put the drum back on and bleed the brakes. Put your wheel back on and drive away.
Jeep Wrangler wheel lug patterns years 1987-2006 are 5X4.5Jeep Wrangler wheel lug patterns years 2007-2014 are 5X5
Remove wheel and brake drum, disassemble brake parts, disconnect brake line from back side, remove 2 bolts holding cylinder on from backside of brake plate, install new one, tighten bolts, attach brake line, reassemble brake, reattach wheel, and bleed brakes.
A piston on each end of the wheel cylinder pushes outward when the brakes are applied. This pushes the brake shoes against the brake drum and stops the vehicle. The pistons are forced out by the pressure of the brake fluid inside the wheel cylinder when you apply the brakes.
You have a blown / leaking wheel cylinder. Replace wheel cylinder.