Looking for high beam lead to trigger off road lights

Tiny
OHSPANMAN
  • MEMBER
  • 2014 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
Want to locate which wire is the high beam lead from the dimmer switch towards the high beam relays. This vehicle has factory HID lights. Looking for high beam lead to trigger off road lights when high beams are actuated.
Thanks
Tuesday, January 19th, 2021 AT 3:02 PM

5 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
These head lamps are a little different in the fact that you have a body controller that receives what is called a CAN bus message from the switch and it interprets that signal and the BCM turns the lights on and off. This means you are not going to be able to tap directly into a switch or voltage feed prior to the BCM. The reason is, that voltage is only 2.5 volts and that is not enough to power your lights nor do you want to interfere with this messaging or a lot of stuff will stop operating.

Here is a guide on this type of system that will help explain what is happening:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

and

https://www.2carpros.com/articles/how-to-check-wiring

What I would do is tap into one of the feeds from the BCM to the high beam itself. So whenever the high beams are on these lights will be on. Or you can tap into it and run a switch to the passenger compartment. Then you will need to turn the high beams on to power the switch, then you can flip the switch to turn these lights on.

Here are the wiring diagrams that show these two wires. Let me know if you have questions on this but you have a couple options so let me know if you need help talking through the best option. https://www.2carpros.com/articles/how-to-check-wiring Thanks
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Wednesday, January 20th, 2021 AT 6:25 PM
Tiny
OHSPANMAN
  • MEMBER
  • 3 POSTS
Thank you for your answer and explanation. After several days under the dash I came to the conclusion, from trial and error, that I was not going to find a wire at the switch location that would serve my purpose. I was looking towards the BCM as my next step. With your information I am headed in the right direction. Thank you for your expertise.
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Wednesday, January 20th, 2021 AT 7:21 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
You got it. Using that output you will be just fine. Let us know how it turns out. Thanks for the update.
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Wednesday, January 20th, 2021 AT 7:41 PM
Tiny
OHSPANMAN
  • MEMBER
  • 3 POSTS
Thanks Kasekenny1. Located connector C2280E and found pins 7 and 8. Connected my lead to my relay, after proving that I had the right connector, and all is great. Thank you for your help. In case someone else has an issue here is a couple of pictures for your interest.
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Thursday, January 21st, 2021 AT 11:09 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
That is great information and I know for a fact someone else will benefit from that. Thanks for the update and sticking with us to update the conclusion.

Thanks for using 2CarPros.
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Thursday, January 21st, 2021 AT 7:23 PM

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