Dimmable Illumination

The illumination dimming level is controlled by the BCM with input from the headlamp switch. The BCM communicates with the headlamp switch using 2 voltage signals, one for the brightness increase and the other for brightness decrease. Based on the dimmer switch input from the headlamp switch, the BCM calculates the dimming level.

The BCM is the master module that controls the dimmable illumination. The BCM accomplishes this by:

• providing PWM voltage directly to backlit switches.
• sending a message over the network to modules that contain integrated backlighting.

Dimmable backlit components that receive voltage directly from a module through a circuit are:

BCM 

• Rough road switch
• Park brake switch
• Hazard switch
• Headlamp switch
• Ignition switch (push button)
• Obstacle avoidance switch
• Steering wheel mounted switches
• Traction control switch

Modules that contain integral Light Emitting Diodes (LEDs) are sent a message from the BCM indicating the backlighting intensity level. The receiving modules use the illumination brightness level message to set the backlighting intensity of internal illumination sources. If a module does not receive the illumination brightness level message or the data received is deemed invalid, the module defaults to full nighttime intensity.

Additionally, if the IPC does not receive the ambient light level message from the BCM for up to 5 seconds, the IPC illumination remains at the last level based on the last message received.

The following modules have dimmable illumination integrated into them:

• GSM
• HVAC module
• IPC