Networked Illumination Operation

The dimmable switches and components are illuminated when the parking lamps are on. The system-wide illumination dimming level is determined by the BCM using the ambient light level input from the light sensor and the requested illumination dimming level input from the dimmer switch. The BCM sends the illumination dimming level message to the GWM on the HS-CAN1.

The GWM distributes the message to the following components:

MS-CAN 

• FCIM
• DDM
• PDM

HS-CAN3 

• IPC
• APIM
• ACM

The receiving modules use the illumination dimming level message to determine the backlighting intensity of internal and external non-networked illumination sources. If a module does not receive the illumination dimming level message or the data received is deemed invalid, the module sets a continuous memory DTC and defaults to full nighttime intensity.

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 nighttime illumination level.

On vehicles equipped with autolamps, if the exterior lamps are activated during the daytime, the message center illumination remains at full intensity and it cannot be dimmed using the illumination 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 illumination panel dimmer switch. The message center illumination changes back to full intensity when the intense ambient light is restored.

The hazard switch is integral to the FCIM and cannot be serviced separately.