Did windshield repair mess up wipers?

I faithfully read your article weekly in the Philadelphia Inquirer, and I have a question that no one can figure out. I have a 2015 Ford Escape SE that does not have the rain sensing option. I had to have my windshield replaced due to a stone hit. I had OEM Ford glass put back in for the replacement. All is fine with the glass part of the work, but now when I turn my key to start the car, I get a slight (1/2 to 1/4 inch) up-anddown movement out of the wiper arms — it could be just the passenger side moving and hitting the driver side arm, which is above it. Neither the internet nor my Ford dealer can explain this, and other Fords don’t do this movement that I have found. The other odd coincidence is my son has a 2016 Fusion. He had his windshield replaced for a stone hit also, and yes, his wiper arms jump also on turning the ignition on. Any help you can offer will be appreciated. The problem is not only annoying; I don’t know if it’s doing any harm to the wipers or motor. Thanks much. — BillW.

Your Escape wiper system is pretty sophisticated! There are two wiper motors, carefully coordinated to insure the wiper blades sweep at the appropriate speed and not collide (many/most vehicles use a single motor with a connecting arm between wiper pedestals). When operated, the wiper switch sends a network message to the SASM (steering angle sensing module) which then passes the request to the BCM (body control module). The BCM continues the process, sending a specific speed/function command to the driver’s side wiper motor. The driver’s side motor then messages the passenger side motor, coordinating speed and sequencing to insure proper wiper arm choreography.

In an additional message, Bill indicated when he first turned on the wipers after the windshield job, the wipers seemed to bind and really jump, and the start-up jitter began occurring after this.

My thought is perhaps the glass installer made a boo-boo reinstalling the wiper arms to the pedestals, creating a misalignment situation and a wrap-up/tangle during the first wiper use. (Ford lists a rather intricate procedure for installation/ positioning to insure collision-free/ full sweeps. The wipers were readjusted during a subsequent repair attempt.) This may have resulted in either a position learn error or damage to one of the wiper motor’s internal position sensors.

Disconnecting the battery for perhaps a half-hour and then reconnecting may be worth a try (this could clear a learn error).

If that doesn’t do the trick, it’s probably best to have a sharp dealer tech take a crack at diagnosis (possible access to an identical/similar vehicle to swap wiper motors may be the most efficient means of confirming a corrupted motor/sensor). Correctly interpreting data between the motors may not be possible.