Autolamps Feature
The BCM also monitors the light sensor with a voltage signal. The light sensor input to the BCM varies with the ambient light conditions.
When the BCM receives a message from the SCCM indicating a request for the autolamps, the BCM monitors the light sensor for the ambient light condition. If the BCM determines the ambient light level is dark, the BCM supplies voltage to the exterior lamps.
If the ignition switch is already in the RUN position and the vehicle enters a dark/lighted area (such as when entering/exiting a non-lighted tunnel during the daytime), the transition from light to dark (or dark to light) needs to last 15 seconds before the BCM turns the exterior lamps on or off. This strategy prevents the exterior lamps from unnecessarily flashing on and off.
The BCM reacts quicker under extreme light conditions. If the BCM has detected a very dark condition, the exterior lamps are turned on after 1.5 seconds. If the BCM has detected a very high ambient light level, the exterior lamps are turned off after 4 seconds.