Chevrolet Trax: Interior lighting systems description and operation

Interior Lamps

The interior lighting consist of two groups. This first group includes lamps that may not be dimmed.

• Dome/reading lamps
• Rear compartment courtesy lamp

Dome Lamps

When any door is opened, the associated door jamb switch closes providing a door open input to the body control module (BCM). The BCM responds by applying battery positive voltage to the dome lamp control circuit illuminating the dome lamp. The dome lamp will turn OFF immediately if the ignition switch is turned to the ON position or approximately 20 seconds after all doors are closed. The dome lamp will normally turn OFF using the theater dimming feature when controlled by the BCM. If the operator inadvertently leaves any interior lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

Keyless Entry Interior Illumination

When the operator uses the keyless entry transmitter in order to unlock the doors, the BCM receives a doorunlock signal. The BCM must receive inputs from various systems that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF, and all doors are closed before the BCM will activate the interior lamps. The courtesy lamps will remain ON for 20 seconds after the door is closed. The BCM will turn off the courtesy lamps OFF through the theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps will turn OFF immediately.

Rear Compartment Courtesy Lamp

The BCM provides battery positive voltage to the rear compartment courtesy lamp. When the rear compartment is opened, the rear compartment latch opens providing a rear compartment open input to the BCM. The BCM responds by applying battery positive voltage to the rear compartment lamp control circuit illuminating the rear compartment lamp.

Reading Lamps

The inadvertent power supply voltage circuit from the BCM provides battery positive voltage the reading lamp.

When the reading lamp switch is activated, the switch contacts close providing a path to ground and the reading lamp illuminates. If the operator inadvertently leaves a reading lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

Interior Lamps Dimming

The second group includes lamps which may be dimmed.

• Door lock switch - driver
• Hazard warning switch
• Headlamp switch
• HVAC control head assembly
• Instrument cluster
• Multifunction switch - center console
• Radio
• Steering wheel control switch - left
• Steering wheel control switch - right
• Transmission shift lever position indicator

When the headlamp switch is placed in the PARK or HEAD position, the park lamp switch signal circuit provides an input to the body control module (BCM). The BCM responds by applying voltage to the park lamps as well as the dimming control circuits illuminating all components with interior backlighting. All LED and incandescent backlighting turns ON at the dimming level indicated by the instrument panel dimmer switch. The instrument panel dimmer switch is a momentary type switch and utilizes a resistor ladder to accomplish dimming controls. The instrument panel dimmer switch contains a battery positive voltage reference circuit and a signal circuit from the BCM. When the instrument panel dimmer switch is held in the decrease brightness position, the BCM receives a low voltage signal via the instrument panel dimmer switch signal circuit. The BCM responds by decreasing the brightness of all interior backlighting by decreasing the voltage supplied to the backlighting components via the dimming control circuits. When the instrument panel dimmer switch is held in the increase brightness position, the BCM receives a high voltage signal via the instrument panel dimmer switch signal circuit. The BCM responds by increasing the brightness of all interior backlighting by increasing the voltage supplied to the backlighting components via the dimming control circuits.

Battery Rundown Protection/Inadvertent Power

The BCM inadvertent power supply voltage circuit provides battery positive voltage to all of the interior lamps.

In the event that any of these lamps were to remain illuminated for a period of more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to prevent total battery discharge.

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