HOW DO YOU REPLACE REAR WIPER MOTOR ON A 2004 JEEP GRAND CHEROKEE

This info taken fro a Jeep Forum. Should be helpful if you want to remove and attempt to repair yourself:
Repair Rear Wiper Motor
Tools you'll need:
Some kind of thin metal rod like a wood nail
Small Flathead Screw driver or knife
Crescent Wrench or correct sized box wrench
Socket Wrench
10mm Socket
Multimeter
Optional: Panel puller for the plastic clips on your hatch panel
Optional: 7mm socket for the gear-box

Clean up:
PB Blaster
WD40
Water
Small Wire Brush
Small-er wire brush that can fit inside a small canister.
Shop Vacuum Cleaner
Elbow Grease

Type of Motor: "Permanent Magnet DC Motor" Google it for information on how it works.



Step 1: Removing the motor
Alright, got your tools ready? Good, let's get to work.

First, remove your wiper arm blade. Accomplish this by pulling the arm back from the back hatch until it stops, insert your small object(I used a nail) into the two small holes on the wiper arm to keep it in place. Now take your screwdriver(I used a knife) and look for the spring loaded tab right next to the output shaft from the motor on the hatch(The tab is attached to the arm). Lift it, and pull the wiper arm off.

Got it off? Great. Now take your crescent wrench and remove the thin nut that's threaded around the base of the output shaft. The plastic cap on the outside of the hatch is now only held on by the motor and fluid hose, be wary of this small part falling and hitting you in the head.

Now open up your hatch and prop it up if it doesn't stay up. Carefully remove your rear panel, or in my case, just rip it off because it's barely held on by the plastic tabs anyway. Set it aside, and unplug your motor from the wiring harness. There's a big black connector, you can't miss it, it's on the passenger side of the motor(NOT the driver's side, there's another connector there that's apart of the motor assembly, you don't need to undo that)

Now that the connector is undone, get to work with your 10mm socket and undo the two bolts that are horizontally parallel to each other. There are four bolts total, two horizontal that hold the silver plate onto the hatch, and two vertical that hold the motor to the silver plate. Fiddle with the motor until it comes out, it'll be a pain in your rear because the wiring harness will get in the way, the output shaft wont wanna come out of the hatch, ect, just fiddle with it until it comes out.

You might also wanna make sure to re-connect the window cleaner hose to the little nipple in case you disconnect it while removing the motor.



Step 2: Diagnosing the motor
Good work, you have the motor out now. As I stated before, this is a Permanent Magnet DC Motor, so it's a big cylinder connected to a gearbox with some fancy wiring do-hickeys. You want to take your multi-meter and check the continuity(14-15ω) of all of the wires; there should be about five and a few of them connect into one another..check everything.

Now there's a few things we should talk about to properly diagnose this motor, if you do a little research on the motor, you'll know what I'm talking about. Let's start.

Wires If any one of the wires are broken, you'll need to solder in some repairs. Obviously electricity isn't getting through.

Brushes If the brushes are to blame, then you can swap these out with a new set. This is an extremely common problem with electric motors, it's caused by prolonged use of the motor, or flat out wear and tear. I'm not sure where to get new brushes, but a good hardware store probably sells them.

Internal Coils The motor can be burned out due to seized gears...you have to remove the cylinder to find out for sure. If your motor is burnt out, this will be evident by the coils, they will be black as opposed to brass. If this is the problem, then just toss the motor back in to fill the gap left by the output shaft and get a new one. It's not worth the time or the effort to re-wire the armature unless you really want to.

Permanent Magnets None of the above? Proceed to step three!



Step 3: If you've made it this far...
Okay, so you've determined whether or not the motor electrically works, that means the brushes are good, that means the power is getting to and through the motor, but nothing is happening? Well, if you haven't already, open up the motor!

Take your small flat head screw driver and find the two metal clips holding the big cylinder to the gearbox. They are parallel to each other on opposite sides of the cylinder. You remove them by inserting the screw driver into the slots on the cylinder itself and prying them out; be careful as they will go flying if you use too much force. Now slide off the cylinder and set it aside.

If your motor has been sitting for awhile and you've made it to this point, you'll find out why your motor doesn't work.

It rusted out. Now again, I'm not an expert, but in all of my experiences with rusty magnets, the magnets loose their properties when rust coats their surface. Once removed, the magnetic grasp is restored. When I removed the armature case from the motor, rust literally poured out from the container. Both of the permanent magnets and the electro magnets were rusted to junk and back. Once the rust was removed, and the magnetic properties were restored, the motor worked again. Simple, right?



Step 4: My method of cleaning the rust
Take your PB blaster and spray a decent amount into the cylinder with the two permanent magnets, let that sit for awhile. Take your wire brush and begin brushing off the electromagnets on the armature as best as you can. DO NOT USE PB BLASTER for the armature. I "don't" know if the chemical will remove the insulating lacquer from the coils, but I have a good feeling it will. As you brush, the armature will spin around and be a pain in the rear, but work with it and get as much of that rust off as you can. This is where you use your elbow grease.

As you spin the armature, you'll notice whether or not the output shaft moves as you spin it. If it moves without resistance, then you don't need the 7mm socket to open the gear box. Most likely the gearbox is fine. If it doesn't, your gears may be seized or stripped. Not too much you can do about this without replacement parts. It's all up to you.

Now go back to the cylinder and take your thin metal brush and dip it into that PB blaster you sprayed in, start brushing all that **** out. What will end up happening is the magnets will begin to work again, and attract all of the rust fragments. Doh! Brush your heart out, and then pour some water into the container and swosh it around to get the PB blaster out, rinse it out a few times and then spray your WD40 into the container to get rid of the water. Take your vacuum cleaner and **** out the remaining rust fragments; use a rag to help brush the fragments out to be sucked up by the vacuum.

Cleaned it up? Good, now put it all back together and throw the motor back into the hatch.



Step 5:
Enjoy your rear wiper blade and smile at the fact that you just saved 120$ on a replacement JY motor that might have had the same problem.

You have to remove the rear door panel cover. The motor is held on by two bolts