Headlights not working?

NIBS3675

MEMBER
2010 FORD F-150
5.4L
V8
4WD
AUTOMATIC
277,000 MILES

I have the truck listed above fx4. I was installing LED headlights onto it, I got them installed and they didn’t work only if you did flash to pass, so I took them out replaced the original headlights back into the truck and now with the original headlights back in still no low or high beam but flash to pass works, all running lights and dash lights come on but no headlights, also noticed the high beam indicator doesn’t come on when the lights are on and you flip the high beams, where should I start?

Thursday, February 6th, 2025 AT 4:08 PM

2 Replies

CARDOCTOR74

MECHANIC
62 POSTS

I would first check all fuses. I will attach a fuse box diagram to check headlight fuses. If fuses are good, you may have two different problems since the low and high beams work differently. The high beam comes out of the interior fuse box off of the high beam relay and goes to both High beams on the yellow wire. If you have power on one, then you should have power on both yellow wires or if there is a broke wire between left and right yellow wire. For the low beam then are powered and controlled separately from within the interior fuse box. You will need to scan the interior smart junction box for internal failure of low beam circuits. Also, you could have shorted out the smart junction boxes on these vehicles go bad without warning due to the internal circuits use small transistors instead of larger relays as they use to in older versions. This is where to start. Fuse box diagram is attached.

https://www.startmycar.com/us/ford/f-150/info/fusebox/2010

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Thursday, February 6th, 2025 AT 6:39 PM

CARDOCTOR74