Autolamps

Autolamps

Principles of Operation

Exterior Lighting

The Steering Column Control Module (SCCM) monitors the headlamp switch position by sending voltage signals on multiple circuits to the headlamp switch. There is one circuit for each headlamp switch position. At any given time, one of the signal circuits is switched to ground. The SCCM (Steering Column Control Module) sends a message to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN), indicating the headlamp switch position.

If the SCCM (Steering Column Control Module) does not detect any active inputs from the headlamp switch for 5 seconds, or if the SCCM (Steering Column Control Module) detects multiple headlamp switch input circuits are active, the SCCM (Steering Column Control Module) sends a message to the BCM (Body Control Module) to indicate the fault. The BCM (Body Control Module) then turns the parking lamps and headlamps on and keeps them on until the battery saver feature times out.

Refer to Exterior Lighting Exterior Lighting in the Description and Operation for information regarding the battery saver feature.

If either situation occurs, the SCCM (Steering Column Control Module) and the BCM (Body Control Module) cannot be ruled immediately as being at fault. This is normal behavior of the SCCM (Steering Column Control Module) and the BCM (Body Control Module) design as a fault has been detected with the inputs from the headlamp switch.

The autolamp feature is enabled when the BCM (Body Control Module) receives a network message from the SCCM (Steering Column Control Module) indicating the headlamp switch is in the AUTOLAMPS ON position.

Autolamps Feature

The BCM (Body Control Module) monitors the light sensor with a voltage signal. The light sensor input to the BCM (Body Control Module) varies with the ambient light conditions.

When the BCM (Body Control Module) receives a message from the SCCM (Steering Column Control Module) indicating a request for the autolamps, the BCM (Body Control Module) monitors the light sensor for the ambient light condition. If the BCM (Body Control Module) determines the ambient light level is dark, the BCM (Body Control Module) supplies voltage to the exterior lamps.

If the ignition is already in RUN 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 (Body Control Module) turns the exterior lamps on or off. This strategy prevents the exterior lamps from unnecessarily flashing on and off.

The BCM (Body Control Module) reacts quicker under extreme light conditions. If the BCM (Body Control Module) has detected a very dark condition, the exterior lamps are turned on after 1.5 seconds. If the BCM (Body Control Module) has detected a very high ambient light level, the exterior lamps are turned off after 4 seconds.

If a fault is detected with the light sensor input, the BCM (Body Control Module) turns the parking lamps and headlamps on.

Headlamps On With Wipers On Feature

When the autolamps feature is active and the front wipers are on for more than 3 seconds (except during a mist wipe or while the wipers are on to clear washer fluid during a wash condition), the exterior lamps are turned on. The exterior lamps are turned off when the ignition is changed to OFF or ACC, the headlamp switch is placed in the OFF position, or the front wipers are off for more than 30 seconds. The exception to this is when the exterior lights are on because of darkness determined by the light sensor.