System Operation

Headlamps

System Operation

System Diagram





Network Message Chart

BCM (Body Control Module) Network Input Messages





SCCM (Steering Column Control Module) Network Input Messages






Battery Saver

NOTE: The battery saver time-out is 1 minute if the vehicle has less than 201 km (125 mi).

NOTE: The battery saver does not control the parking lamps if the headlamp switch is in the PARKING LAMPS ON position.

To save battery voltage, the BCM (Body Control Module) provides automatic shut-off of the interior and exterior lamps after a time-out period when the ignition is off. The BCM (Body Control Module) monitors the ignition state and input from the RKE (Remote Keyless Entry) system to determine when to energize or de-energize the battery saver relay and to shut the power off to the lamps. A timer in the BCM (Body Control Module) starts when:

- the ignition changes to OFF,

- any door or liftgate becomes ajar while the ignition is off,

- an UNLOCK button of the RKE (Remote Keyless Entry) transmitter is pressed while the ignition is off,

- a valid keypad code is entered while the ignition is off,

- or the courtesy lamp switch (integrated into the FLM (Front Lighting Control Module)) is used to turn the courtesy lamps on while the ignition is off.

When 10 minutes have elapsed, the BCM (Body Control Module) automatically shuts off voltage to the lamps. The timer restarts (voltage is restored if the BCM (Body Control Module) is in battery saver mode) if:

- the ignition transitions out of OFF,

- any door or liftgate becomes ajar,

- the UNLOCK button of the RKE (Remote Keyless Entry) transmitter is pressed,

- a valid keypad code is entered,

- the courtesy lamp switch is pressed.

Low Beams

The headlamp switch is integrated into the FLM (Front Lighting Control Module). The FLM (Front Lighting Control Module) monitors the headlamp switch position and sends a headlamp switch status message over the communication network to the BCM (Body Control Module) to indicate the headlamp switch status (position or a fault with the headlamp switch).

If the BCM (Body Control Module) detects a fault from the headlamp switch or loses communication with the FLM (Front Lighting Control Module), the BCM (Body Control Module) turns the parking lamps and headlamps on and keeps them on until the battery saver feature times out (REFER to Battery Saver). If either situation occurs, the BCM (Body Control Module) cannot be ruled immediately as being at fault. This is normal behavior of the BCM (Body Control Module) design as a fault has been detected with the inputs from the headlamp switch.

When the BCM (Body Control Module) receives input requesting the headlamps on, it supplies voltage to the headlamp bulbs (halogen headlamps) or the ballasts (HID (High Intensity Discharge) headlamps) within each headlamp assembly.

Vehicles with halogen headlamps use single filament bulbs.

Vehicles with HID (High Intensity Discharge) headlamps utilize ballasts to provide the necessary voltage to illuminate the HID (High Intensity Discharge) bulbs.

The BCM (Body Control Module) also provides an overload protection of the low beam output circuits. When an excessive current draw is detected, the BCM (Body Control Module) disables the affected low beam circuit driver. REFER to Field Effect Transistor (FET) Protection .

High Beams

The SCCM (Steering Column Control Module) monitors the multifunction switch for a high beam or flash-to-pass request. When the multifunction switch is in the HIGH BEAM or FLASH-TO-PASS position, the SCCM (Steering Column Control Module) sends a high beam_flash-to-pass request message to the BCM (Body Control Module) over the communication network indicating the request.

When the low beams are on and the BCM (Body Control Module) receives a request for high beams, the headlamps remain powered and the shutter within each headlamp is activated. This changes the headlamp beam pattern to illuminate a greater distance.

The BCM (Body Control Module) also provides an overload protection of the high beam output circuits. When an excessive current draw is detected, the BCM (Body Control Module) disables the affected high beam circuit driver. REFER to Field Effect Transistor (FET) Protection .

Flash-To-Pass

The SCCM (Steering Column Control Module) monitors the multifunction switch for a high beam or flash-to-pass request. When the multifunction switch is in the HIGH BEAM or FLASH-TO-PASS position, the SCCM (Steering Column Control Module) sends a high beam_flash-to-pass request message to the BCM (Body Control Module) over the communication network indicating the request.

When the low beams are off and the flash-to-pass is requested, the headlamp bulbs and the shutters are activated for approximately 0.5 second. When the low beams are on and the flash-to-pass is requested, the shutters within the headlamps are activated as long as the multifunction switch is held in the FLASH-TO-PASS position.