Installing Aftermarket LED (2021 CX-5)

[Terrypham]

Hi everyone,

I’m installing an aftermarket LED light for my 2021 CX5 and trying to tap into the fuse box in the engine bay for power. The problem is, whatever fuse I use, it stays on even when the car is off. What did I do wrong, am I missing anything? I hardwired my dashcam before and it was straightforward, but I’m so confused right now.

Thanks in advance!

Zoom zoom

 

[200955]

Keep in mind that some LED's are polar in nature which requires the positive lead on the bulb to be 12V+ only. And if you mistakenly use a "switch-back" bulb where it doesn't belong strange things can occur. A bit more detail would be nice, like, what kind of light you're installing and why you need a new power feed.

 

[Terrypham]

Keep in mind that some LED's are polar in nature which requires the positive lead on the bulb to be 12V+ only. And if you mistakenly use a "switch-back" bulb where it doesn't belong strange things can occur. A bit more detail would be nice, like, what kind of light you're installing and why you need a new power feed.

Hi thanks for replying.

It’s a exterior 12V LED strip to put under the hood so it has nothing to do with the car’s existing lighting system. I’m trying to figure which fuses are switched but seems no luck so far.

 

[RedBaron]

trying to tap into the fuse box in the engine bay for power. The problem is, whatever fuse I use, it stays on even when the car is off. What did I do wrong, am I missing anything?

Many/most of the fuses in the fuse box ARE powered all the time. You'll need to search through them with a meter to find one that is off when the car is off (if there are any).

Also, if you are using a fuse tap (AKA Add-a-fuse) make sure that you put it in the right way round, or you can be supplying power direct and not through the fuse (test for power when the fuse is removed).

If you want your LEDs on with the DRLs, you can attach it to the DRL relay, but you'll need an inline fuse then. See pics:

 

[Terrypham]

That’s peak engineering right there holy cow . Yeah I don’t have a meter at the moment but from my experience wiring my dashcam, the current goes right to left so it’s potentially very difficult to tap-a-fuse given how tight that place is.

Thanks so much for the photos and suggestion, I think I’ll go that DRL relay route instead

 

[Mazdiod2]

Hi thanks for replying.

It’s a exterior 12V LED strip to put under the hood so it has nothing to do with the car’s existing lighting system. I’m trying to figure which fuses are switched but seems no luck so far.

Hmm. Something from amazone? Does it go on when you open the hood, or you want it on with the headlights?

 

[Terrypham]

Hmm. Something from amazone? Does it go on when you open the hood, or you want it on with the headlights?

Yeah you’re right on that. It’s supposed to turn on with the head light

 

[N7turbo]

Not sure what the objective is, but my car collects enough bugs, I wouldn't want to attract them to the inside of the engine bay.

 

[Terrypham]

Not sure what the objective is, but my car collects enough bugs, I wouldn't want to attract them to the inside of the engine bay.

Entirely aesthetic but you have a good point . I don't have problem with bugs tho but I’ll see how it goes haha