* Wiper arm is misaligned: The arm might be slightly bent or improperly attached, causing it to wipe too low.
* Wiper blade is worn or damaged: A worn or damaged blade can't make proper contact with the glass, leading to skipping and sticking.
* Window is dirty or has debris: Dirt, grime, or even a small pebble can interfere with the wiper's movement.
* Wiper motor is weak or failing: A weak motor might not have the power to overcome the friction of a stuck blade.
* Wiper linkage is damaged or worn: The mechanism connecting the motor to the arm could be broken, bent, or seized.
Here's a troubleshooting and repair guide:
1. Inspect the Wiper Blade: Remove the wiper blade and inspect it for wear, tears, or damage. Replace it if necessary. Even a small amount of damage can cause issues. Ensure you get a blade specifically designed for your Jeep Grand Cherokee.
2. Clean the Window: Thoroughly clean the rear window, paying close attention to the area where the wiper arm makes contact. Remove any dirt, debris, or ice. Use a glass cleaner and a clean microfiber cloth.
3. Check Wiper Arm Alignment: With the wiper arm OFF, carefully inspect the arm itself for any bends or damage. Also, check how securely it's attached to the wiper motor linkage. A slightly misaligned arm can cause it to wipe too low. You might be able to gently adjust it by hand, but if it's significantly bent, it may need replacement. Be extremely careful not to break anything when adjusting.
4. Test the Wiper Motor: Turn the rear wiper on. Does it move freely? If it's slow, jerky, or doesn't move at all, the wiper motor may be failing and need replacement. This is a more involved repair.
5. Inspect the Wiper Linkage: This is the more complex part. You'll likely need to consult a repair manual specific to your 1999 Jeep Grand Cherokee to understand how the wiper linkage is assembled. Look for any signs of wear, breakage, or binding in the linkage mechanism. This often requires partial disassembly of the rear wiper assembly to diagnose.
6. Adjust the Wiper Arm (if possible): If you suspect misalignment, try to adjust the wiper arm slightly. However, be very careful; forcing it can cause damage. A slight upward adjustment might be all that's needed. Consult a repair manual for specifics.
Important Considerations:
* Repair Manual: A repair manual specific to your 1999 Jeep Grand Cherokee is highly recommended. It will show you diagrams of the wiper system and provide step-by-step instructions. You can find these online or at auto parts stores.
* Safety First: Always disconnect the battery's negative terminal before working on any electrical components, including the wiper motor.
* Professional Help: If you're uncomfortable working on the wiper system yourself, it's best to take your Jeep to a qualified mechanic. Replacing the motor or linkage can be complicated.
By systematically checking these items, you should be able to pinpoint the cause and fix your rear wiper problem. Remember to take your time and be careful to avoid causing further damage.
