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Home >> Mercury >> 2005 >> Montego Base, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Cluster And Panel Illumination >> Diagnosis And Testing >> Instrument Cluster and Panel Illumination >> Pinpoint Test >> Pinpoint Test A: The Control Illumination Is Inoperative >> Normal Operation

Normal Operation

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.