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Backup and Rock lights


PathyDude17
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A relay is either on or it's off, so you wouldn't get a dim glow out of the ground lights. If it's not enough power to light LEDs properly, I'll bet it's not enough power to keep a relay engaged. And having the relay coil giving that trickle of current an easier path to ground might clear up your dim dome light glow at the same time. I'd want to test both theories before drilling holes and running wires, of course.

 

The lights I bought weren't name-brand, but the Amazon ad did claim an IP67 rating. And it was wrong!

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40 minutes ago, PathyDude17 said:

So, your concern is that the glowing dome light is indicative of the circuit not having enough power to run anything else off of? 

 

 

I think he's saying that it means the circuit isn't completely off when it's supposed to be off, so you may find yourself driving down the road with lights on underneath your vehicle, which is illegal in many places.

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19 minutes ago, mjotrainbrain said:

 

I think he's saying that it means the circuit isn't completely off when it's supposed to be off, so you may find yourself driving down the road with lights on underneath your vehicle, which is illegal in many places.

Not a problem in Idaho. Am I right to assume though that the light would not be as bright as usual, as it is with the dome light?

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32 minutes ago, PathyDude17 said:

Not a problem in Idaho. Am I right to assume though that the light would not be as bright as usual, as it is with the dome light?

 

Not if you were going to wire it with a relay.  If the slight power in the circuit is enough to trip the relay you'll be rockin full brightness.

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Oh, good point. I looked up what other people in different vehicles have done. I saw a jeep with 6 lights tapped into the existing dome wire and a silverado with 4 tapped into the existing wire. Also a guy who did two tacomas who said he did one with a relay, and the relay rattled and shut off mysteriously then came back on after a few weeks. The other truck he did led strips and rock lights on existing wiring with no issues. All the Jeep forums seem to have real confusion with wiring relays and lots of people have followed wiring diagrams only to not get the lights to work. My two LED's would be quite low amp draw, so I'm starting to reconsider a wiring splice.

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For what it’s worth, I’ve run 3 different LED set ups in my dome & cargo light without any dim lighting of the LEDs (I have this effect in the driver door light of my wife’s MDX - though not the other 3 doors )

It sounds like your goal is really puddle lights. Rock lights are usually undercarriage so you can see in front of your wheel in the dark, & sometimes behind & inside under the truck with the right placement. Upper fender mounting just causes shadow where the rubber hits the ground, which is counter productive. Once my major stuff is done, I’d like to install some. I’ve needed to spot rocks & obstacles in the dark countless times. Once I do that I might even put an undercarriage camera as my new radio has 2 camera inputs & I’ll often have to spot myself.

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Interesting......Correct. Just calling them rock lights out of not knowing what else to call them (and that happens to be the name of the products I'll be buying). Puddle lights is a much better word for it. But yeah, I want to be able to see ice and rocks and whatever else. I'm feeling pretty confident I can just tap into the existing wire, though.

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Doubt that'd be a problem.  I've added 3 LED pods to the dome light wiring without issue.  The relay approach is if you plan to add a fair amount of extra lights.  I interpreted rock lights to be a few LED strips mounted all around the vehicle, and in that case, it'd probably work just tapped off the wire, but a relay would be the better approach.

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Ha, yeah, those specs must've gotten lost in the shuffle while everyone had these grand visions of undercarriage lighting.  If you're just talking about a pair of these, tapping off the line shouldn't be a problem at all.

 

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Sorry, what I'm saying is that I doubt the small amount of power that's keeping the dome light dimly on would be enough to trigger the relay. It takes a certain current through the coil to close the contacts, and if the smart entry thingus is leaking so little power that it barely does your dome lights, I doubt it would be enough to keep the relay engaged and the undercarriage lights on when they shouldn't be.

9W at 12v would be 0.75A, x2 is 1.5A. If you've swapped the rest of the circuit to LEDs I'd be surprised if you didn't have the headroom for that.

The reason I'd tend towards relaying them is just to keep the circuits separate, so that if the lights below the vehicle got damaged and shorted out, the blown fuse wouldn't take out your dome light as well. Does seem overkill for those tiny lights, though, unless you're going full Fast and the Furious under there.

Edited by Slartibartfast
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Well, thanks for the confirmation on that @hawairish. Only other question is where you chose to access that wire? Is there one spot easier than the other, just curious. And I'm also assuming your pod's light up properly with the dome light without any problems haha

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5 minutes ago, Slartibartfast said:

Sorry, what I'm saying is that I doubt the small amount of power that's keeping the dome light dimly on would be enough to trigger the relay. It takes a certain current through the coil to close the contacts, and if the smart entry thingus is leaking so little power that it barely does your dome lights, I doubt it would be enough to keep the relay engaged and the undercarriage lights on.

9W at 12v would be 0.75A, x2 is 1.5A. If you've swapped the rest of the circuit to LEDs I'd be surprised if you didn't have the headroom for that.

The reason I'd tend towards relaying them is just to keep the circuits separate, so that if the lights below the vehicle got damaged and shorted out, the blown fuse wouldn't take out your dome light as well. Does seem overkill for those tiny lights, though, unless you're going full Fast and the Furious under there.

Thanks for the clarification. Nah, just two lights to add a little convenience lighting. No show truck lighting here

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Right on.  Easy test is just pull the dome light down and rig up the connections.  Should light up fine.

 

My pod installs are in the liftgate, there are some details in the link mjotrainbrain posted earlier.  Your access point will depend on your placement of the pods and length of wire.  There are few grommets on under seats, trying to run through those might be an option to save from drilling new holes.

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5 minutes ago, hawairish said:

Right on.  Easy test is just pull the dome light down and rig up the connections.  Should light up fine.

 

My pod installs are in the liftgate, there are some details in the link mjotrainbrain posted earlier.  Your access point will depend on your placement of the pods and length of wire.  There are few grommets on under seats, trying to run through those might be an option to save from drilling new holes.

Sweet, that's super helpful info. I'll look for those. I'm also putting in a separately wired reverse light, so hopefully I only drill one hole or can use one of those grommets.

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2 minutes ago, PathyDude17 said:

Sweet, that's super helpful info. I'll look for those. I'm also putting in a separately wired reverse light, so hopefully I only drill one hole or can use one of those grommets.

 

Reverse lights are easy, no drilling required.  Just pop off the taillight and tap into the wire to the reverse bulb.  There's enough clearance space back there. 

 

618057-CB-F5-B5-4002-A2-E1-C9-B908-A7-BB

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Mine are wired for reverse only, and I don't intend on changing that (I'll be wiring additional exterior lighting and separate controls eventually), but adding a switch wouldn't be difficult.  My backup lights have a fairly low current draw, so I would just bypass the signal for the park/neutral position sensor (AT) or back-up switch (MT) through another switch.  Rather than tap wires at those switches (they're installed on the transmission), the wires are in the harnesses in the front passenger footwell.  This saves the trouble of having to run wires to the back of the truck.

 

There are a few ways of doing this, though, and if your backup lights have higher current demands, you may need to run a dedicated wire to them and use a relay to get both reverse and manual modes.

 

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Alright. That makes sense. I’m glad I at least figured out that the some wiring isn’t a problem, as that was my main concern. Amp draw on my backup light will also be fairly low, it’s just a 20W. Maybe low enough to wire into the dome wiring as well as my puddle lights. What are the specs on your pods?

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