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Hello, my name is***** and thanks for your question.
Is the vehicle equipped with auto lamps?
Is the vehicle equipped with daytime running lamps?
Ok thanks. Just FYI, the lighting control system on this vehicle is the most complex and most difficult to diagnose system ford ever designed, especially if you don't have a ford scan tool. I'm not trying to push you off. Here is how this system works.
The headlamps are controlled by the front electronic module (FEM) and instrument cluster module (IC). The headlamp and multifunction switches are hardwired to the instrument cluster. When the headlamp switch is in any position, the instrument cluster module will send a command to the FEM through the SCP communication network. The FEM will process this information and output the appropriate command to the headlamps, which are hardwired to the FEM. This is the same for the high beams and flash-to-pass functions, which are controlled by the multifunction switch. That being said the concern you have can be caused by several issues. The IC could be corrupt and sending false on signals to the FEM. The FEM can be corrupt and be energizing the headlamps without being commanded. There could be a wiring issue between the headlamp switch and the IC. Both of these modules have on board diagnostics which can be accessed with a dealer level scan tool. They also have on board monitoring capabilities which can be accesses with a dealer level scan tool. Inputs and commands can be monitored as well as network activity between the modules. The headlamps are powered continuously, the FEM controls them by adding or removing ground. So you know the power side is OK, and you have a control issue which I cannot even begin to lead you in diagnosis with out a dealer level scan tool. I usually get negative ratings from answers like this, but I wanted to at least let you know what is involved in this system and what you are up against.
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