Networked Illumination Operation

The dimmable switches and components are illuminated when the parking lamps are on. The instrument panel dimmer switch, which is integral to the headlamp switch, controls all dimmable interior illuminated components. While the ignition switch is in the ACC or RUN position, the headlamp switch/ instrument dimmer switch illumination is dimmable. The BCM sends the illumination command through a LIN circuit to the switch.

On vehicles equipped with autolamps, if the exterior lamps are activated during the daytime, the message center illumination remains at full intensity and does not dim from the instrument panel dimmer switch. If the vehicle travels under a bridge or through a tunnel, the low level of ambient light causes the illumination level of the message center to change to the level set by the instrument panel dimmer switch. The message center illumination changes back to full intensity when the intense ambient light is restored.

If the IPC does not receive the dimming level or ambient light level network messages from the BCM for up to 5 seconds, the IPC illumination remains at the last level based on the last message received. If the IPC receives invalid or no signals for more than 5 seconds, the IPC defaults to full night illumination level.

Based on the ambient light level and dimming level messages, the BCM sends the illumination dimming level message to the HVAC module, DDM and PDM on the MS-CAN and also to the IPC APIM, FCIM and FCDIM on the HS-CAN1.

There are 3 active modes that the illumination system can be in. (In the inactive state all backlit components and modules are OFF.)

• Daytime and exterior lights OFF. (The state of night time and exterior lights OFF is identical to the daytime and exterior lights OFF mode).
  • When the headlamp switch is in the OFF state, the illumination system is in daytime and exterior lights OFF mode. Therefore, all displays as well as the PRNDL indicators go to their full daytime brightness level while all other illumination system components that do not have daytime illumination are completely off. The driver has no possibility to adjust or influence the maximum daytime illumination level but the ambient light sensor can accomplish this automatically.

• Night time and exterior lights ON.
  • When the headlamp switch in any position other than OFF and the ambient light sensor has detected night time or twilight conditions, the illumination system is in the night time and exterior lights ON mode. All illuminated components illuminate dependant on the dimmer switch input signal. The dimmer switch allows the driver to adjust or dim the illumination level of the controls and displays for optimum visibility and legibility in addition to compensation done by the ambient light sensor signal.

• Daytime and exterior lights ON.
  • When the headlamp switch in any position other than OFF and the ambient light sensor has detected daytime light level conditions, the illumination system is in the daytime and exterior lights ON mode. The BCM ignores the dimmer switch input since the ambient light sensor input indicates daytime conditions. All bezel illumination signals go to the minimum illumination brightness. All display illumination signals go to the maximum illumination brightness. The PWM non-networked signal from the BCM causes the components that have daytime illumination to have a minimum illumination brightness. All other components will illuminate their graphics or symbols at a barely discernible level to prevent washout conditions. All displays as well as the PRNDL indicators go to their full daytime brightness illumination level. The driver has no possibility to adjust or influence this illumination level since the dimmer switch input is ignored.

On vehicles equipped with an ambient light sensor, the message center provides a setup menu to select manual or automatic illumination levels based on ambient light levels. For additional information, refer to the Owner's Literature.