LED light bar and fog light installation

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=139386
Printed Date: May 13, 2025 at 8:43 AM

Topic: LED light bar and fog light installation

Posted By: radolla
Subject: LED light bar and fog light installation
Date Posted: September 03, 2015 at 4:33 PM

Hi, I have a LED light bar installed on my truck that works just fine. Now I want to install fog lights, I have a On-off-on rocker switch and would like it to work so that I can have both the Light bar and Fog lights on or just the fog lights. I have 2 relays one has 2 87 pins on it and the other is just a regular 4 pin. The problem I am having is how do I make this work without back feeding to the light bar. I have included a picture, hope this helps!

posted_image

Replies:

Posted By: howie ll
Date Posted: September 03, 2015 at 6:13 PM

You just need to add a diode (1N4004).
fog_lights_and_led_light_bar.png
For simplicity sake I've ignored 87a, not used anyway.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: radolla
Date Posted: September 03, 2015 at 6:45 PM

Are these automotive diodes or regular ones? also silly question how would one install it in line with automotive wire?

Posted By: howie ll
Date Posted: September 03, 2015 at 6:54 PM

All the same, the most commonly available diode.
Solder.
Daft questions.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: radolla
Date Posted: September 03, 2015 at 6:55 PM

Rock on, Thanks for the help. Ill give it a shot!

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