Dear Car Talk:
I know my car intimately. We're on a first-name basis, and I am quite familiar with what is working correctly and what is out of whack. So when I took my Ford Fusion to the dealer, telling him that there was something wrong with the timing of my intermittent wipers, of course he found nothing amiss. I told him that it didn't happen every time I turned the wipers on, but every now and then the timing of the wipes was weird.
That was three years ago. It's only gotten gradually worse since then. Now, when I turn off the wipers, they sometimes stop mid-wipe, in the center of the windshield. That's not good. Also, sometimes the intermittent setting works, and sometimes the wipers just keep wiping continuously regardless of the setting. -- Marge
We believe you, Marge. The problem is most likely a bad wiper motor. The wiper motor contains the circuitry that's supposed to make the wipers finish their current wipe, and park themselves at the bottom of the windshield, no matter where they are when you turn them off. But it also could be a bad wiper switch. The switch (the multipurpose switch on the steering wheel stalk) sends a current to the motor. And if the current is inconsistent, that could cause strange wiper behavior.
The best way to test the switch is to have the wipers misbehave when the mechanic has the car at the shop. That way, he can test the current at the wiper motor. If the current doesn't change while the wipers misbehave, then the switch is fine. That means it's almost certainly a bad wiper motor. Either way, it's going to "wipe" a few hundred bucks out of your checking account, Marge.
And you may want to consider searching for a mechanic who is more inclined to believe you. While a wiper motor might not be a life-or-death issue, you'd like to know that if you came in complaining of something potentially serious, your mechanic wouldn't brush you off as "that wacky Marge who's on a first-name basis with her car." You want him to say: "Oh, that's wacky Marge. She's on a first-name basis with her car, but she knows what she's talking about."