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JK Electrical, Lighting & Sound SystemsBulletin board forum regarding topics such as stereo head units, CD players, MP3 players, speaker systems, amplifiers, hardmounted GPS devices, computers, headlight upgrades, fog lights, off-road lights, general wiring and anti-theft devices.
I admittedly am no electrical wizard so this is really interesting to me. Reading a few threads about this brings up a couple questions I have. The wires that run to those particular dome lights (and into the light in back of a JKU) are definitely thinner than most the wiring in the jeep from what I recall. So you're implying the thinner wire has higher resistance and inductance, and that if the wires were thicker to start with then they might be able to power the OPs strips better? Also, I never thought about how RGB lights require more power than just standard white. Not sure that applies to the OP but that is interesting as well. What stumps me a bit is I have an LED strip hooked to these wires in the back of my JKU and it has maybe 12 LEDs in it and works just fine. They are just white LEDs though. They appear to be lit at full strength to me but maybe not. I have LED strips run to several places in the jeep (tapped into the same source) and have no issues with needing capacitors......is that maybe just cuz the thicker wire is helping?
These are white 12V LED lights that I got from Amazon - specifically because they said 12V. The are fully lit and bright when on the constant power (solid yellow) wire, but don't turn off if in "standby mode" (door, key and/or stalk) or in off mode if the engine is on. Otherwise, normal functionality when wired to yellow w/stripe (dome), but extremely weak or not fully lit up. What bugs me is the OEM light bulb is 12V. Shouldn't 12V = 12V? Why would the dome wire be so much weaker?
Ok Bagadonuts, here is a real world comparison test for you cuz this is how I roll. I came home and yanked out my front dome light. Test patient is a '13 JKU sport. I unplugged the wire from the back and this is what I got going on (black, solid yellow, yellow/brown stripe....in that order) -
Black is negative, solid yellow is 12v triggered by the door opening or the stalk switch, and yellow with brown is 12v that would be operated by the on/off buttons at the light. I had an extra scrap strip of LED 5050 lights laying around with 50 LEDs in it. Using paperclips shoved in the wire harness and some wire with aligator clips pinned to my multimeter I get the reaction I'd expect. Probing the leads to the LED strip with the yellow wire I get full strip lights on when the door is open, off when the door is closed and vehicle is running, on/off appropriately with the stalk switch. When probing the LED strip with the yellow/brown wire I get lights on full time regardless of anything else, as to be expected since that is constant 12v that would be off/on with the factory switch. I also do not see any dimming, browning, or burnout in any of the LEDs on that strip....and keep in mind there are 50.
The wiring colors have changed between our years as mine was yellow/brown and yours was yellow/white, but I'd expect to see the same functionality. Do you have a multimeter that you can test the wires with and then probe the LED like I did so you can see what the voltage is doing while the light is on?
On a final note, I must have been misremembering from back when I wired my rear strip cuz those wires to the harness appear to be same size as all the other wiring in the jeep.
Ok. So I need MORE LEDs to make this work? I tried to wire 12 LEDs facing the front of the car (driver and passenger) and 12 facing back. So maybe I should try to double?
My friend has a multimeter so I have to wait until he has time.
Thanks for your effort. I will keep you all updated and hopefully with pics when it works.
My personal opinion is that # of LEDs don't matter....for example I have 5" strips down in my footwells and up in my speaker boxes and they work just fine with with just a couple lights. I'm a little stumped in general cuz I do see valid points in Sandau's comments above, I'm just not sure if it applies or not. Part of me is like you....12v is 12v, and every LED I have hooked up on the jeep and on my camping trailer is simple 12v and works fine....regardless of a lot of lights or a couple lights, so idk. I wish I had a better scientific or electrical expertise to explain. At least with a simple multi meter though you can see what is happening to the voltage as you're testing things out. If I still had it taken apart I'd try it again with just a short snippit of the string but I suspect my results would be the same.
Curious to hear any other responses if any show up.
Ok. Got the LEDs to stay on full bright with either constant power (SOLID) or dome light wire (STRIPED), so I wired in the STRIPED. New problem: They don't turn off while driving. Doesn't matter where the stalk position is or anything else. Lights stay on while driving. Tried a different strip of lights, still stay on while driving. Lights come on/off with door, key remote or stalk, which is great. Also turn off at the stalk. Any ideas? Do I need a resistor? I got multi-meter readings:
STRIPED: Engine running: 14V, Engine off/everything off 4.5V, Stalk ON/Door Open ON/Key Remote Activated 12.8V.
SOLID: Engine running 3.5V, Engine off/everything off 3V;Stalk ON/Door Open ON/Key Remote Activated 12V
Maybe the dome light is the solid? Either way, I wired the LEDs to both yellow wires (not at the same time) and the lights stay on while driving on either wire.
Don't know why, but now the strip LEDs work to replace my dome light. Works off of key fob, stalk and doors. Must be a "Jeep thing" lol. I do have LED "glow", but according to my research, most likely coming from CANbus voltage that is always on. My jeep is my daily driver and started up fine the next morning and I have some quick wire connectors for when I am not using the Jeep for a while. Not very bright and does not distract while driving - my switch pod lights are brighter. Pics are below, one with glow and one on. I have blue for the front to match radio, usb charger and switch pod LEDs and a white for back. Way brighter and more useful than original setup. Thanks for the help!
08-10-2021, 06:34 AM
I have LED strips run to several places in the jeep (tapped into the same source) and have no issues with needing capacitors......is that maybe just cuz the thicker wire is helping?
I wish I had a better scientific or electrical expertise to explain. At least with a simple multi meter though you can see what is happening to the voltage as you're testing things out. If I still had it taken apart I'd try it again with just a short snippit of the string but I suspect my results would be the same.
