Operation

OPERATION

AUTOMATIC HEADLAMP SYSTEM


Automatic headlamps are controlled by the Body Control Module (BCM). With the headlamp switch in the AUTO position, the BCM will control the headlamp, parking, side marker, tail and instrumentation lamps based on ambient light levels. Ambient light levels are monitored by the BCM using the Day/Night signal and Electrochromatic Mirror (ECM) present from the Compass Mini Trip (CMTC) located on the front windshield in front of the rear view mirror ECM. Ambient light readings are averaged to limit cycling the lamps ON and OFF when passing through areas with varying light levels. The automatic headlamps will only function when the engine is running with RPM > 450. When the headlamp switch is in the AUTO position (Automatic mode), the Headlamp Time Delay system will function when the ignition switch is placed in any position other than run/start.


DAYTIME RUNNING LAMPS


Power is reduced using pulse-width modulation to the high beams, where by the power is switched on and off rapidly instead of remaining on continuously. The duration and interval of the power pulses is programmed into the FCM. Daytime running lamps are functional when 450 rpm's are reached.


HEADLAMP SYSTEM


The headlamp system will default to headlamps ON position when ignition switch is ON and when an open or short circuit failure occurs on the headlamp switch input or PCI data bus communication between the BCM and the FCM fails. The system will return to normal operation when the open or short is repaired. A fault will be reported by the BCM when a failure occurs on the dimmer or headlamp switch input.


If the exterior lamps are ON and the headlamp switch is in any position other than OFF or AUTO and with the ignition switch OFF (LOCK) after 3 minutes the BCM sends a message via PCI bus to the FCM informing the FCM to turn off the headlamps, park lamps and fog lamps. This feature prevents the vehicle battery from being discharged when the vehicle lights have been left ON.


HEADLAMP TIME DELAY SYSTEM


The headlamp time delay system is activated by turning the headlamps ON (high or low beam) while the engine is running, turning the ignition switch OFF, and then turning the headlamp switch OFF within 45 seconds. The system will not activate if more than 45 seconds elapse between ignition switch OFF and headlamp switch OFF. The BCM will allow the headlamps to remain ON for 90 seconds (configurable) before they automatically turn off (If the key is in the ignition during the headlamp time delay mode, then both the headlamps and park lamps (including panel dimming) will be ON).


If the headlamp switch is in the Auto Headlamp Position, the headlamps are ON due to the night signal from the CMTC and the ignition switch is in any position other than run/start, the BCM shall enter a 90 second (configurable) Auto Headlamps time delay mode. If the key is in the ignition during the headlamp time delay mode, then both the headlamps and park lamps (including panel dimming) will be ON. If the key is not in the ignition, then only the headlamps will be ON. The BCM will allow the headlamps to remain ON for 90 seconds before they automatically turn OFF.


OPTICAL HORN/HIGH BEAMS


When the multi-function switch is pulled to the first detent (optical horn) signal, the headlamps are ON, key-in the ignition the BCM shall send a message via PCI bus to the FCM to turn on the headlamps drivers to illuminate all four filaments (Low and High beams). When the multi-function switch is pulled to the second detent (high beam) signal and the headlamps are ON, the BCM shall send a message via PCI bus to the FCM to turn on the headlamps drivers. The High Beams are illuminated and the Low Beams and Fog Lamps (if ON) are extinguished. If the headlamps were in the high beam configuration when power was removed from the headlamps, the headlamps will be configured as low beam the next time they are activated.


NOTE: For RG - Export vehicles, the low beams and front fog lamps will remain ON when high beams are activated.