Principles of Operation

PRINCIPLES OF OPERATION

Hardwired Dimmable Illumination

NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).

When the parking lamps or the headlamps are on, the SJB monitors the input from the instrument panel dimmer switch. The SJB sends a pulse-width modulated (PWM) voltage to the dimmable switches and control components based on input received from the instrument panel dimmer switch.

Networked Controlled Dimmable Illumination
The SJB sends a message over the medium speed controller area network (MS-CAN) to the heating ventilation air conditioning (HVAC) module - electronic automatic temperature control (EATC), the audio control module (ACM), and the instrument cluster (IC) to indicate the backlighting intensity level. When any module does not receive the illumination signal, it defaults to full nighttime brightness. Full nighttime intensity is equivalent to the illumination level when the parking lamps are on, and the instrument panel dimmer switch is in the highest setting.

Non-Dimmable Illumination
When the ignition switch is in the START or RUN positions, the delayed accessory relay provides voltage from the SJB to the non-dimmable components.