|North American Grand Cherokee Association|
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Rear Wiper Reconditioning
The rear wiper on the
Grand Cherokee is problematic at times. The design allows moisture
inside around the shaft housing and trapping it there, causing
corrosion. Eventually, the wiper motor won't be able to turn the
shaft. Fortunately, it's not too hard to fix.
My rear wiper started to act up. It simply wouldn't move when I flicked the switch. I discovered that I could get it started by gently pushing the wiper arm with my hand. Be careful, though. Don't push too hard or you'll damage the splines on the shaft or on the wiper arm. I finally grew tired of getting out in the rain to get the wiper started, so I decided to fix the problem instead of treating the symptoms.
First of all we need to remove the wiper arm. Flip up the lid at the bottom of the arm and remove the nut beneath it. Then remove the arm by gently pulling it straight out. You may have to wiggle it carefully, but make sure you don't damage the splines. Then there is a large nut by the hatch itself. Remove it carefully, so you don't scrape the paint.
Then we need to remove the wiper motor. In order to get to it, we must first remove the inside panel from the hatch. There are a large number of screws holding this. Most of them are clearly visible, but two of them are skillfully hidden beneath the fabric. Two slight indentations are the only visual clues of their existence.
Once the panel is removed, you can easily get to the wiper motor. It's held in place by two bolts, which are, for once, easy to get to. Then there is an electrical connector with a small tab that you need to depress in order to remove it. You're now holding the wiper motor in your hands, and it's time to take it inside to work on it.
There is a plastic lid over the circuit board that is easy to remove. Then you can see the circuit board, which you need to remove by using a soldering iron to loosen the two leads indicated by the red arrows in the picture to the right. (The big lump at the lower left-hand corner is the actual electrical motor.)
Now you need to remove the black piece of plastic covering the shaft and gear. It's held in place by the four bolts indicated by the red arrows below. Once that's out of the way you'll see the plastic gear attached to the shaft (you can see a part of it through the rectangular hole in the picture). The shaft needs to come out, but this can be difficult if there's a lot of corrosion on it. We used a plastic hammer to carefully knock the shaft out. We had to knock it back and forth a few times before it would come loose. Be careful not to bend the shaft or damage its end. Do not use a metal hammer. An alternative way of doing this might be to use a large vise and press the shaft out of its housing.
There is also a short piece of pipe on the shaft where it comes out of the housing. This is the culprit, because water will leak in through it and get trapped in the cavity beneath it. Once you've gotten the shaft out, gently polish it to remove any corrosion. Then do the same on the inside of the shaft housing.
Before putting it all back together, you should do a small test. Using a 12V DC power supply, or simply a car battery, apply voltage to the two motor terminals (shown in the first picture above) to verify that the motor is working. Test both directions by reversing the polarity. If the motor is working, don't open it. If it's not, you'll most likely need to get a new one.
Insert the shaft into its housing. It should be fairly obvious how to install it, because of the gear. Then put the black piece of plastic back with its four bolts, and solder the circuit board back on. Then snap the lid on and go out to your Jeep again. Insert the electrical connector and put the motor assembly back with its two bolts. At this time you should verify that it's working. You need to close the hatch first, because the wiper won't move if the hatch is open. Turn on the ignition, start the rear wiper and make sure that the shaft is rotating as it should in both directions. Move the switch to the OFF position and let the motor stop before switching the ignition off. This will ensure that the shaft is in the clockwise end position, which you need to know before putting the wiper arm back. Don't forget to put the big nut on before setting the arm in place.
We put some silicone grease on the short pipe on the shaft to try to seal it against moisture. The hatch panel should be re-installed last. The two hidden screws beneath the fabric are tricky to put back in place, but it's not impossible. Tighten all screws well, to avoid the annoying rattle from loose panels. Done!
North American Grand Cherokee Association
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