B0189 CADILLAC - Sunload Sensor 2 Circuit Performance
Faulty Sunload Sensor 2
Sunload Sensor 2 harness is open or shorted
Sunload Sensor 2 circuit poor electrical connection
Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module
Engine Light ON (or Service Engine Soon Warning Light)
B0189 Cadillac Description
The sunload sensor is a 2-wire photo diode. The vehicle uses left and right sunload sensors. The two sensors are integrated into the sunload sensor assembly along with the ambient light sensor. Low reference and signal circuits enable the sensor to operate. As the sunload increases, the sensor signal decreases. The sensor operates within an intensity range between completely dark and bright. The sensor signal varies between 0-5 volts. The Heating, Ventilation, and Air Conditioning (HVAC) Control Module converts the signal to a range between 0-255 counts. The sunload sensor provides the HVAC control module a measurement of the amount of light shining on the vehicle. Bright or high intensity, light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.