Autolamps

Overview

The autolamp system consists of:

• Light sensor
• Headlamp switch
• BCM

The autolamp system provides light sensitive automatic on/off control of the exterior lamps. The autolamp system keeps the exterior lamps on for a preselected period of time after the ignition is turned off (20 seconds is the factory default setting). The preselected time lapse is adjustable up to approximately 3 minutes. To change the autolamps time delay, refer to Autolamps Time Delay Adjustment .

System Operation

System Diagram

Network Message Chart

  BCM Network Input Messages

Autolamps

The BCM 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 headlamp switch status 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 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.

Headlamps On With Wipers On Function

When the headlamp switch is in the autolamps on position, the exterior lamps turn on when the front wipers are on for more than 3 seconds (if wipers are turned on manually) or 30 seconds (if the wipers are on from the rain sensing wiper system). This feature does not activate the exterior lamps during a mist wipe or while the wipers are on to clear washer fluid during a wash condition.

The exterior lamps turn off when the ignition is changed to OFF or ACCESSORY, the headlamp switch is placed in the OFF position, or the front wipers are off for more than 30 seconds (60 seconds if on from the rain sensing wiper system). The exception to this is when the exterior lights are on because of darkness determined by the light sensor.

Component Description

Light Sensor

The BCM sends a voltage signal to the light sensor. The light sensor provides resistance between the voltage signal and ground. The resistance varies depending on the amount of ambient light detected by the light sensor. The brighter the ambient light, the lower the resistance. By varying the resistance, the BCM can determine the amount of ambient light.