Circuit Description
WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) provides a constant output reference voltage of 5 volts for the proper operation of the ambient light sensor. The constant output reference voltage supply ensures that variations in the output signal of the ambient light sensor are due to changes of the sensor rather than variations in the voltage supply. The BCM monitors the constant output reference voltage and sets a DTC when the output is not within the expected range of 4.75-5.25 volts.