Abstract: A moisture sensing assembly for controlling vehicle accessories such as windshield wipers is mounted on the inner surface of a vehicle window or windshield for detecting moisture on the outer window surface. A plurality of infrared energy emitting diodes and a sensor for receiving reflected infrared energy from the window and any moisture thereon are mounted at predetermined angles and spacing in a support. The support is biased against the window and enclosed in a protective housing detachably mounted to a window mounted plate preferably adjacent a rearview mirror on the front windshield. The support preferably includes an infrared energy monitoring sensor adjacent the emitting diodes which may be combined with or separate from an ambient infrared energy sensor. The monitoring and ambient sensors provide reference energy levels allowing compensation for varying diode output due to temperature and age and varying external vehicle light conditions.