Interior Lamps Dimming

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

The second group includes lamps which may be dimmed. This group may use a combination of light emitting diodes (LED), pulse width modulation (PWM) voltage illumination and dimming control through serial data.

Accessory Power Receptacle - Instrument Panel
Audio/Video Input Adapter
Door lock switch - left rear
Door lock switch panel control module - left rear
Door lock switch - right rear
Door lock switch - driver
Door lock switch - passenger
Door lock switch panel control module - right rear
Heater and air conditioning user interface control - front
Front Overhead Console Assembly
Info Display Module
Dimmer Switch
Instrument panel cluster control module
On/Off Vehicle Switch
Head - up display switch
Vehicle Stability Control System Switch
Hazard Warning Switch
Single Charge Only 2nd Row Receptacle - Floor Console Rear
Radio
Rear compartment lid unlatch switch
Rear audio Control Module
Seat memory switch - driver
Steering wheel controls switch - left
Transmission range selector controls

With the headlamp switch 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 backlight dimming control circuits illuminating all components with interior backlighting. All interior backlighting turns ON at the dimming level indicated by the Dimmer Switch. The instrument panel Dimmer Switch is a variable resistance rotary type switch. A voltage signal is sent to the switch and the switch is grounded via a low reference circuit to the BCM. The signal will vary with resistance (switch position) and the BCM will measure the value through the switch signal circuit. The BCM interprets the signal and applies a pulse width modulated voltage through the backlighting control circuits illuminating the interior backlighting to the requested level of brightness. The BCM simultaneously sends a serial data message to the Instrument Panel Cluster Control Module, Info Display Module, Transmission Range Selector Controls, Heater and Air conditioning User Interface Control, Front Overhead Console Assembly, Read Audio Control Module, and the Radio.