Recalibrate wiper sensor?

Hey all! I have a windshield wiper problem. My windshield wipers do not work on the sensing intermittent setting. They do work for the low/high speeds.

I bought my Prius used and noticed the previous owners had replaced the windshield. I'm guessing they never had the sensor recalibrated. I talked with the dealer and they want to charge me for two hours of labor to have it recalibrated. Anyone know how I could do it myself?

 

They will wipe once if I increase the sensitivity, which is just how the car is programmed, but won't do anything afterwards. They also work if the windshield is frozen over, as I unintentionally discovered over the winter. Telling this to the dealer is what led them to tell me I need to recalibrate the sensor.

 

Thank you so much, you're the best! Would you mind pointing me in the right direction for finding instructions for the on-vehicle inspection? I poked through the link you so helpfully provided for the repair manual but there's a lot and I'm not 100% sure of what I'm looking for. Does this perhaps involve the Toyota Techstream diagnostic system?

 

A long overdue update - to anyone having a similar problem, the sensor tape was simply missing. Whoever did the windshield replacement didn't do a thorough job. New rain sensor tape (part number 89944-48010) cost about $2.50 plus shipping for the replacement when it was purchased from West Coast Toyota of Long Beach. This totaled about $10 versus the $175 the Toyota dealership wanted to even diagnose the issue.

The install is super easy and took about 10 minutes, mostly due to my being very careful and cleaning everything. Instructions follow:

On the front bottom of the rain sensor is a small plastic slide tab. Slide it toward the bottom of the windshield - the tab does not detach, it simply slides. This will unlock the rain sensor, which then pulls off in a plane perpendicular to the plane of the windshield.

In this case, both the sensor and the corresponding section of windshield were dirty and 90% isopropanol was used to thoroughly clean both. The rain sensor tape (which is in actuality more a transparent gummy plastic) was then adhered directly to the rain sensor, starting at the bottom and rolling it toward the top to avoid air bubble formation. The sensor was then replaced on the windshield, again pushing directly into the windshield to avoid skewing the gummy tape. One tiny bubble was formed from this step but does not seem to affect performance. The slide tab was then pushed back into place, locking the assembly. Now it works great - take that, Portland rain!

Thanks again to kithmo, alanclarkeau, and Elektroingenieur for their knowledge and assistance.