* Wipers Arms are misaligned: The most common cause. The wiper arms may be improperly installed, bent, or have come loose. This prevents them from completing their full sweep. Check for any visible bends or looseness at the connection points.
* Wipers Linkage is Damaged or Broken: The mechanism that connects the wiper motor to the arms might be worn, broken, or dislodged. This includes parts like the pivot points, connecting rods, or the transmission itself. A broken or seized linkage will restrict movement.
* Wipers are worn out: Worn-out wiper blades can sometimes bind or catch on the windshield, preventing full movement. Replace them with new blades of the correct size.
* Windshield Damage: A crack or imperfection near the wiper's sweep area could be interfering with the wiper's path. Inspect the windshield carefully.
* Park Position Sensor: Some wiper systems have a park position sensor that tells the motor where to stop. If this sensor is malfunctioning, it might be causing the wipers to stop prematurely. (Less likely, but possible).
* Wiper Motor Problem: While less likely to cause stopping *at the edge* specifically, a weak or failing wiper motor could lead to inconsistent or incomplete sweeps.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the wiper arms, linkages, and the windshield for any obvious damage or misalignment. Look for any signs of rust or wear.
2. Wiper Blade Replacement: Replace the wiper blades with new ones, even if they don't seem excessively worn.
3. Check Wiper Arm Attachment: Ensure the wiper arms are securely attached to the linkage. Try gently rocking them to feel for looseness.
4. Wiggle the Linkage: Gently move the linkage by hand to see if it moves freely. Look for any binding or points of resistance.
5. Professional Help: If you're not comfortable inspecting the linkage or motor yourself, take your vehicle to a mechanic or auto repair shop.
By systematically checking these points, you should be able to pinpoint the source of the problem. Remember safety first – disconnect the battery's negative terminal before working on any electrical components.
