Diagnostic Aids

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Dirt/debris on windshield can cause B117A Windshield Outside Moisture/Ambient Light and Humidity Sensor to not work properly.
Sensor needs to be properly seated against windshield. Air gap can cause improper operation.
Due to the sensitivity of the sensor, the wipers may swipe once upon start up or rapid lighting changes. This is normal operation and does not need any further diagnosis.