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Home >> Ford >> 2009 >> Flex Limited, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 2018 (Instrument Cluster Illumination And Panel Illumination) >> Diagnosis And Testing >> Instrument Cluster and Panel Illumination >> Pinpoint Tests >> Pinpoint Test B: All Dimmable Illumination Does Not Dim >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2010 Lincoln MKX and 2010 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

The Smart Junction Box (SJB) sends a voltage signal to the instrument panel dimmer switch. The signal is routed through a variable resistor within the instrument panel dimmer switch and then back to the SJB  to an internal ground. When the dimmer switch is in the lowest setting, the resistance is low. When the SJB  senses the voltage is low (switch in the lowest setting), the dimmable backlighting intensity is low. When the SJB  senses the voltage signal is high (switch in the highest setting), the dimmable backlighting intensity is bright. If the signal is too high (an open circuit or short to voltage), the SJB  faults the dimmable backlighting to full nighttime brightness. If the dimmer switch input circuit is short to ground, the SJB  interprets this as the lowest setting and sets the backlighting to the lowest intensity level, appearing to be inoperative.

Based on input received from the instrument panel dimmer switch, the SJB  sends a message over the network to the backlit modules indicating the backlighting intensity level and a Pulse Width Modulated (PWM) voltage to the hardwired dimmable illumination sources.

The SJB  also sends a message over the Controller Area Network (CAN) to the Audio Control Module (ACM), the Rear Entertainment Module (RETM), the HVAC module, and the Instrument Cluster (IC) to indicate the backlighting intensity level. If the receiving module receives invalid backlighting data from the SJB  for 5 seconds or less, the receiving module defaults the backlighting to the last setting.

If the receiving module does not receive the backlighting status message from the SJB  or if the data received is deemed invalid for more than 5 seconds, the receiving module sets a communication message-related DTC in continuous memory and defaults the backlighting to full nighttime intensity.

This pinpoint test is intended to diagnose the following: 

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