Dimmable Illumination

WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

The illumination dimming level is controlled by the BCM. The BCM sends 2 voltage signals to the headlamp switch, one for the brightness increase and the other for brightness decrease. Based on the dimmer switch input from the headlamp switch, the BCM calculates the dimming level.

The dimmable illumination sources are controlled directly from a voltage supplied circuit by a module, indirectly from the BCM by sending a network message to a module that contains backlighting (such as the IPC, or from a module that receives the backlighting message and provides voltage directly to the switch or through communication to the switch over a LIN circuit.

The BCM is the master module that controls the dimmable illumination. The BCM accomplishes this by:

providing PWM voltage directly to backlit switches.
sending a message over the network to modules that contain integrated backlighting.
sending a message over the network to modules that in turn provide PWM directly to backlit switches.

Dimmable backlit components that receive voltage directly from a module through a circuit are:

NOTE: Some components are optional and are not equipped on every vehicle.

BCM

Adjustable pedal switch
Exhaust brake/roll stability control switch
Hazard flasher/stability control switch
Headlamp switch
Heated rear seat switch
Ignition switch (push button)
Lane departure switch
Mode select switch (MSS)
Overhead console/front dome lamp switch
Spot lamp switch
Stability assist disable switch
Steering wheel mounted switches
Tailgate release switch
Upfitter auxiliary switches

Modules that contain integral Light Emitting Diodes (LEDs) are sent a message from the BCM indicating the backlighting intensity level. The receiving modules use the illumination brightness level message to set the backlighting intensity of internal illumination sources. If a module does not receive the illumination brightness level message or the data received is deemed invalid, the module defaults to full nighttime intensity.

Additionally, if the IPC does not receive the ambient light level message from the BCM for up to 5 seconds, the IPC illumination remains at the last level based on the last message received.

The following modules have dimmable illumination integrated into them :

NOTE: Some modules are optional and are not equipped on every vehicle.

FCIM
FDIM
IPC