Lariat LED DRLs not working as DRL, only on with other lights

[User79]

You can also check the dedicated drl wire to make sure it's got voltage when it should. That would at least maybe rule out the headlights as the problem......it's possible you have a faulty BCM. I attached a PDF of the headlight plug

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[HarryD]

The DRLs do actually work, just not unless the headlights or parking lights are on.

 

[User79]

The DRLs do actually work, just not unless the headlights or parking lights are on.

Those lights have a dual purpose. When the parking lights/headlights are on they are in park light mode & are powered by the parking light wire (pin 5) & are dimmed (the dimming function is within the headlight). In drl mode they are powered by pin 6 (dedicated drl wire) & are at 100% brightness. Pin 6 is the wire I was referring to....If it does not have voltage when in drl mode then it could be a BCM issue, if pin 6 does have voltage then it could be an internal headlight issue but unlikely both headlights are faulty. When the parking lights/headlights are on pin 6 will not have voltage but pin 5 will.

Pin 6 is only difference between xlt & lariat headlight wiring....the xlt headlights are not wired to pin 6 (on the actual headlight) & pin 6 is not activated in bcm on the xlt trucks....that is why forscan is needed for those that did the swap, otherwise they would behave exactly like yours are now except drl would be on low beam on the xlt.

Does this make sense?

 

[HarryD]

Thanks Justin, I see what you are saying now. I did not realize that there are two separate lines running these lights and at different voltage levels. At this point I am going to let Ford Service figure it out.

 

[HarryD]

I had my first service visit to Ford where they addressed the transmission cable clip - was found it to be seated.
Regarding the DRLs only on when other lights were on, the tech. turned my headlight to Auto ( while I was waiting for dealership to open I had headlights turned off while listening to the stereo) and they are now working normally!! Maybe a glitch in the headlight switch??

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