Why does the right low beam headlight not work?

TONISIO

MEMBER
2018 FORD F-150
3.5L
6 CYL
2WD
AUTOMATIC
44,000 MILES

Passenger side headlights have no voltage at the headlight bulb connector when engine starts. Get battery voltage with engine off. Could the issue be the headlight control module? My warranty has just expired. Please advise. Thank you.

Sunday, July 24th, 2022 AT 7:07 PM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Let's check the fuses first, here is a guide to help you and the fuse (f20, f13 in the BCM lower right kick panel - #f76, f15, f61, f95 and f25 in the under-hood panel - locations in the diagrams below, this guide can help you as well.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Also, I have included the headlight wiring diagrams so you can see how the system works. If everything is okay, I would say the BCM is out but to be sure we can do a CAN scan, you can get a CAN scanner from Amazon for about $30.00. here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is a scanner link:

https://amzn.to/3o41KcZ

I have included the BCM replacement instructions in case this is the problem. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

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Monday, July 25th, 2022 AT 10:38 AM

TONISIO

MEMBER
2 POSTS

Hello Ken,

Thank you for all of the valuable information you sent me. Turns out that the LED headlights I had just upgraded to did not consume enough power for the BCM in my truck to recognize to it would remove the power from that circuit. I have to order some decoders to simulate the power consumption of regular halogens. Hopefully it will work. Thanks again.

Sincerely,
Tony

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Wednesday, July 27th, 2022 AT 9:55 AM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Okay, yep that will do it, there are no more regular circuits, everything is monitored and then shut down if something doesn't measure up voltage and amperage wise. Let me know if the decoder works.

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Thursday, July 28th, 2022 AT 9:54 AM

TONISIO