A common cause of this is a loose nut for the wiper arm pivot. Look for a plastic cap over the pivot that can be snapped loose and raised up. Sometimes you have to tug rather hard. Under that cap you should see a nut, typically about a 15 mm nut. Be sure the arm is in the correct position, then tighten that nut about a quarter to half turn. Snap the over back down and you're done. The clue here is the wiper system will be as quiet as normal, and, if you grab the non-moving wiper arm, you can move it across the windshield by hand. Also, sometimes the arm will move sporadically or not far enough, and sometimes it will come down too far and go off the windshield. Any movement when the motor is running proves the hidden linkage is okay.
If tightening that nut does not help, the arm underneath is likely broken. On some vehicles we used to remove the assembly, then weld the arm to its shaft. That would prevent the repeat failure which could happen to a new assembly. Those parts are originally just pressed together. The clue to this is the linkage will be clanking around making noise when the wiper motor is running.
On some models the wiper linkage can fall apart. The connections are snapped together. Depending on which connection comes apart, the linkage might make a banging noise or it could be quiet. If it is quiet, you might hear some unusual scraping or banging noise when you move the wiper arm by hand. If you can reach the linkages and snap them back together, there is a good chance the problem will occur again soon. Typically the ball and socket are worn out and parts must be replaced. Sometimes a wiper arm stuck in ice will cause the linkage to pop apart from the stress on it when the motor tries to run. If that is the case, free the wiper arm, then reconnect the linkage, and that should be the end of it.
Friday, December 9th, 2016 AT 4:56 PM