Normal Operation
WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) monitors the input from the instrument panel dimmer switch when the parking lamps are on. The SJB sends a pulse-width modulated (PWM) voltage to the dimmable components based on input received from the instrument panel dimmer switch. The SJB also sends a message over the medium speed controller area network (CAN) to the electronic automatic temperature control (EATC) (if equipped), the audio unit and the instrument cluster to indicate the backlighting intensity level. If the SJB detects a concern with the circuitry to the instrument panel dimmer switch, the SJB defaults the backlighting to a predetermined intensity level.