Circuit/System Description

WARNING: This page is about a different car, the 2007 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.09 and 4.9 volts depending on outside lighting conditions. The HVAC control module provides a low reference ground and a 5-volt reference signals to the ambient light sensor. The HVAC control module monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. The HVAC control module sends a signal to the body control module (BCM) via class 2 serial data commanding the BCM to turn the front turn signal lamps on steady (non-flashing). Any function or condition that turns on the headlamps will cancel the DRL operation. With the turn signal/multifunction switch in the OFF position, the turn signal lamps will either be turned ON or OFF after a 30 second delay, depending on whether daylight or low light conditions are sensed by the ambient light sensor.