Fog Lamps

The fog lamps are activated by a momentary command originating in the headlight switch assembly. Each push of the fog lamp switch toggles the fog lamps ON to OFF and OFF to ON. The fog lamp switch sends an analog signal interpreted by the BCM. The BCM interprets the analog message, and based on the data, the BCM commands the requested action to turn the fog lamps ON, OFF or to fault the system due to open circuit or short to ground. When the BCM input from the headlight switch assembly indicates the fog lamps are selected, it controls fog lamp operation by providing a battery voltage output to the fog lamps through the right and left fog lamp control circuits. The BCM also provides a battery saver load shedding feature for the fog lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes when the status of the ignition is LOCK, if there is a charging system failure or if the electrical system voltage falls below about 11.75 volts for more than 30 seconds.

FOG LAMPS AND IGNITION STATES 

Fog Lamps - Key-ON - The BCM will turn on the fog lamps when the momentary command button in the headlight switch is pushed and will keep the lamps active until the control button is acted upon again. The headlight switch must be rotated into either park lamps or low beams before the fog lamps can be activated.

Fog Lamps - Transition from Key-ON to Key-OFF - Whenever the ignition transitions to Key-OFF, the fog lamps will be turned off and the fog lamp command will not be reset. This means that at the next Key-ON, the fog lamp will remain turned on. The BCM retains the last state at Key-OFF.

Fog Lamps - Transition from Key-OFF to Key-ON - If the headlight switch is pressed during an ignition transition to Key-ON, the fog lamp will default to its last known state. After the fog lamp switch is released, next activations of the fog lamp switch will be honored by the BCM. Note that the fog lamps will not be activated during a remote start event.

FOG LAMP STRATEGY - FOG LAMP DROPOUT with HIGH BEAMS ACTIVATED 

If the fog lamps are active and the high beams are activated, the fog lamp outputs will turn OFF and the Instrument Panel Indicator (IPC) indicator, commanded by a BCM Controller Area Network-Interior High Speed (CAN-IHS) signal, will also turn off and remain off until the high beams are turned OFF.

If the high beams are active and the fog lamp switch is actuated, the physical outputs and the IPC indicator will remain OFF. The BCM keeps track of fog lamp requests and will honor the requests once the high beams are turned OFF.

CORNERING LAMPS Key-ON 

This function optimizes the front lighting beam when the vehicles moves along a curve at a low rate of speed. This feature is activated once all of the following conditions are satisfied:

• Vehicle PROXI indicates that the cornering light feature is present on the vehicle
• Ignition state is RUN (Key-ON)
• Vehicle is not in (R  ) Reverse
• Low beams are ON
• Hazard Lamps are OFF
• Vehicle speed is equal to or lower than 40 kilometers per hour (kmh) 25 miles per hour (mph)
• Vehicle speed signals are detected and read by the BCM
• Vehicle steering wheel angle indicates that the steering angle is at an acceptable value

If any of these conditions are not satisfied, the BCM will immediately turn off the cornering lamps function. Additionally, if the vehicle is equipped with an Engine Stop Start (ESS) system, the cornering lights will not be turned off during ESS events.

The cornering lamps function comprises two strategies, based on the steering angle or on the turn lamp signal respectively. Both functions will be used when the cornering lamp function is active. In case a conflict arises between the two functions, the functionality based on the steering angle will be given priority to operate the system. In this scenario, the BCM commands the two fog lamps separately based on steering angle values indicating the steering wheel is beyond the "10 and 2" positions when turning. The degree value in the steering angle signal determines if the right or the left lamp will be turned on. Both fog lamps will be turned off if the absolute value of the steering angle indicates that the steering wheel is resting between the "10 and 2" positions.

If the cornering lamps are going to be turned on based on the turn lamps, the cornering lamp simply follows the activated turn signal lamp is turned ON and will deactivate once the turn signal lamp is OFF.

FOG LAMP FAULT MANAGEMENT 

If the BCM receives a short or open circuit from the fog lamp switch, the BCM will set a Diagnostic Trouble Code (DTC) for each faulted condition. If the BCM receives an open or short circuit while the fog lamps are ON, then the BCM will retain the last state of the fog lamp switch until the next engine cycle. After the next engine cycle and the switch is still faulted, the BCM will not activate the fog lamps.