2018 Explorer Base Additional Brake Light Help

[Firav]

Howdy y'all!

I have a 2018 Base Explorer that I'm looking to add an additional LED break light to. These lights link into the emergency lighting system that is being equipped into the vehicle. Where I'm getting hung up is how to intercept the brake light signal so that those LED lights trigger.

I've thought about directly splicing the wires leading to the tail lights/third brake light, but I've been told that causes issues with the transistors in the BCM. Then thought of possibly just installing a relay with its own independent power supply from the battery and just using a trigger wire splice to trip the relays. However, I'm not sure if that would still be enough to cause issues with that BCM.

Another option I've researched is using the trailer light connections from the towing package. The only issues I have with using that harness is that the lights would be powered when the turn signals are turned on as well, instead of it just being strictly the brake lights, and that I'd also be permanently tying up my towing package harness into that deployment (as if I'm going to tow anything with this car anyhow lol).

What would y'all say is the best deployment for something like this? I'm stuck at a crossroads and would like some input from folk that are much smarter than me!

 

[J_C]

Welcome to the forum!

First off, have you checked TN law regarding vehicle lighting? It is possible that you can only have two brake lights, and that they're red.

If your add-on lights use a very small amount of power, then you can probably get away with just taking a tap from the existing power feed to either light, or split half between each existing light if that is possible for what you're adding.

If more power is needed, yes it is better to just use the power feed to the existing light to activate a relay to switch a separate fused run from the battery, and that should not use enough current to make a difference (typically somewhere between 5 mA to 25mA for a 12V relay trigger current is common but any decent major brand relay manufacturer should have a datasheet telling you if you had a different need to know situation, but even if you can't determine specific current, it shouldn't be enough to make a difference with a normal automotive relay).

Why do you feel that you need additional brake light(s)? I've never noticed anyone state that they weren't visible enough... in proper working order.

Wherever you tap in, I would put a fuse right after the point of that tap, and one rated significantly lower than the existing fuse for that power feed, so that if something goes wrong and the add-on shorts out, it does not also take out your factory brake lights. They may even be on two separate fuses from the factory, because it is so important that they not both fail simultaneously.

 

[Firav]

Welcome to the forum!

Hey, thank you! This place is great!

First off, have you checked TN law regarding vehicle lighting? It is possible that you can only have two brake lights, and that they're red.

I have, however, if I were to follow the literal wording of that law, my vehicle would already be out of compliance while being stock lol.

If your add-on lights use a very small amount of power, then you can probably get away with just taking a tap from the existing power feed to either light, or split half between each existing light if that is possible for what you're adding.

If more power is needed, yes it is better to just use the power feed to the existing light to activate a relay to switch a separate fused run from the battery, and that should not use enough current to make a difference (typically somewhere between 5 mA to 25mA for a 12V relay trigger current is common but any decent major brand relay manufacturer should have a datasheet telling you if you had a different need to know situation, but even if you can't determine specific current, it shouldn't be enough to make a difference with a normal automotive relay).

The two lighting units that I plan on installing draw 1A each. I guess what I need to find is a wiring diagram for those brake light circuits to figure out what they're rated for. From there it would be obvious which installation would be the best for the circuit. (I just really don't want to blow a BCM lol)

Why do you feel that you need additional brake light(s)? I've never noticed anyone state that they weren't visible enough... in proper working order.

I don't necessarily need additional brake lights. I'm installing these as part of an emergency lighting package anyhow and they just so happen to have this feature, so I figured I'd use it as well.

Wherever you tap in, I would put a fuse right after the point of that tap, and one rated significantly lower than the existing fuse for that power feed, so that if something goes wrong and the add-on shorts out, it does not also take out your factory brake lights. They may even be on two separate fuses from the factory, because it is so important that they not both fail simultaneously.

Definitely! I'd definitely need to do a lot more research before I know which fuse would need to be put in place.

 

[willyboyrat]

I added 2 ions red color for added brake lights just tapped into the 3rd stop light circuit never had an issue in over 2 years