Normal Operation

WARNING: This page is about a different car, the 2010 Ford Pickup, 2010 Ford F550 Super Duty, 2010 Ford F450 Super Duty, and 2010 Ford Cab & Chassis. 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 by sending a voltage signal to the instrument panel dimmer switch. The return signal is sent back to the SJB . Based on the input from the instrument panel dimmer switch, the SJB sends a Pulse Width Modulated (PWM) voltage to the dimmable illumination sources. If the SJB detects a concern with the circuitry to the instrument panel dimmer switch, the SJB defaults the backlighting to a full intensity level.

The SJB also sends a message over the Medium Speed Controller Area Network (MS-CAN) to the Audio Control Module (ACM) (except base AM/FM), the Rear Entertainment Module (RETM), the HVAC module and the Instrument Cluster (IC) to indicate the backlighting intensity level. The Trailer Brake Control (TBC) module receives the message on the High Speed Controller Area Network (HS-CAN) from the IC .

If the ACM (except base AM/FM), the RETM , the IC or the TBC module receives invalid or missing backlighting data from the SJB , the receiving module defaults the backlighting to full intensity.

If the HVAC module receives invalid or missing backlighting data for 5 seconds or less from the SJB , the HVAC module defaults to the last setting received. If the HVAC module receives invalid or missing backlighting data for more than 5 seconds from the SJB , the HVAC module defaults the backlighting to full intensity.

DTC B2212 (Panel Dim Switch Out Of Range) - an on-demand DTC that sets when the SJB detects an open or short to voltage from the dimmer switch input circuit.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Instrument panel dimmer switch
SJB