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Best to all...

Have a 2004 Rubicon that I am changing the OEM Tails for new LED units. Purchased the $139 pair of Quadratec LED Tail Light Kit for 01-06 Jeep Wrangler TJ. (Comes with replacement flasher also for the LEDs.) Note: the OEMs worked as advertised but like all 15 year old equipment was " drab" compared to modern LEDs.


Installed went fine on driver side, plug fit OE harness plug perfect and have a good ground. Issue I'm having is :

*Head Lights ON: All lights illuminated...Tail, Brake, Backup...turn signal will flash if activated.
* Head Lights OFF: Turn Signal will flash if activated.
* Brake Activation: ALL lights illuminated...tail, Brake, and Backup
* Stick to REVERSE: ALL lights illuminated...tail, Brake, and Backup

QUadratec sent me a second set (GREAT Customer Service OBTW) but have the same symptoms on the second set driver's side

Other clues:
* Swapped pax and drivers LED units to see if just a bad unit...same issues.
* Harness has three distinct inputs that do NOT mix at the harness (like I said, OEMs worked as they should illuminating at the right time wise.)

Anybody have any hints? Similar problems? Solution?

THanks all.

--TimberGhost sends
 

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Put the stock flasher in and see what they do. They may flash faster but it just a test to see if there is a change. If this changes nothing get your multimeter out and verify what's going at the connector (Jeep side), check for the three different voltage sources, brake, turn, etc.
 

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Welcome! You've done a good job of troubleshooting so far.

Pretty sure the PCM controls all lights - it looks for a certain resistance from the incandescent bulbs to work properly however the replacement flasher should accommodate the differences. I would completely back up and restore to standard lights, make sure everything is working okay. Then put the replacement flasher in and change just the taillight bulbs - see if that works.

Another idea is find a truck stop, they usually have a good selection of various lights, LED and incandescent; buy a couple of LED marker lights and temporarily hook them to the tail lights or front turn signal (that would be easier to access.

I never bothered to change my tail lights to LED - every one I've ever seen had bad LEDs.
 

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Welcome! You've done a good job of troubleshooting so far.

Pretty sure the PCM controls all lights - it looks for a certain resistance from the incandescent bulbs to work properly however the replacement flasher should accommodate the differences. I would completely back up and restore to standard lights, make sure everything is working okay. Then put the replacement flasher in and change just the taillight bulbs - see if that works.

Another idea is find a truck stop, they usually have a good selection of various lights, LED and incandescent; buy a couple of LED marker lights and temporarily hook them to the tail lights or front turn signal (that would be easier to access.

I never bothered to change my tail lights to LED - every one I've ever seen had bad LEDs.

When I put LED's in mine they just flashed faster. I added a resistor at the lights and went back to normal.


The reason I suggested putting the old flasher back in is because the replacement may be an electronic flasher and may not be playing nice.
 

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Best to all...

Have a 2004 Rubicon that I am changing the OEM Tails for new LED units. Purchased the $139 pair of Quadratec LED Tail Light Kit for 01-06 Jeep Wrangler TJ. (Comes with replacement flasher also for the LEDs.) Note: the OEMs worked as advertised but like all 15 year old equipment was " drab" compared to modern LEDs.


Installed went fine on driver side, plug fit OE harness plug perfect and have a good ground. Issue I'm having is :

*Head Lights ON: All lights illuminated...Tail, Brake, Backup...turn signal will flash if activated.
* Head Lights OFF: Turn Signal will flash if activated.
* Brake Activation: ALL lights illuminated...tail, Brake, and Backup
* Stick to REVERSE: ALL lights illuminated...tail, Brake, and Backup

QUadratec sent me a second set (GREAT Customer Service OBTW) but have the same symptoms on the second set driver's side

Other clues:
* Swapped pax and drivers LED units to see if just a bad unit...same issues.
* Harness has three distinct inputs that do NOT mix at the harness (like I said, OEMs worked as they should illuminating at the right time wise.)

Anybody have any hints? Similar problems? Solution?

THanks all.

--TimberGhost sends
Is it only the DS giving you problems?
The symptoms you are listing sound a lot like a poor ground.
Can you try running a temporary dedicated ground back to the battery to confirm that is not your problem?
LED's are more susceptible to poor grounds, as they illuminate with much less current flow than incandescents.
 

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Discussion Starter #6
Hey All...just a follow up to let everyone know the final outcome.

First, thanks to all who chimed in, I appreciate your insights.

Both LED tail lights installed now and working as advertised. THe problem? BOTH lights have to be installed for them both to work properly. (Remember I was working the driver side only but I had removed BOTH taillight devices in prep for install.) Once I put one mounting bolt in the pax side the driver side started to work! To prove that was the fix I ungrounded the pax side and voila, back to the previous non-working symptoms.


I do NOT know why this would have to be...old bulbed devices appeared to work as advertised independently. Any EEs out there who can explain?


Anyway, again, thanks all. On to LEDing my front turns and marker lights. Anybody else done this and have any stories/tips so I don't run into something similar?


Happy trails...jh sends
 

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I installed the savvy LED tail lights and liked them so much. I then went to install led bulbs in the front markers and ended up removing them. I had issues with them actually work. I don't know why they didn't work properly but in the end just removed them and out the old bulbs back in. I had the resistor in the steering column replaced so the rears would flash properly however with all lights LED they didn't want to function properly. perhaps I had gotten some bad LED or they were just cheap ones and that's why. I didn't try to track down the problem so don't know. Keep us posted if you do swap out the bulbs on the front.

I am running quadratec stealth LED head lights and love them. They work great and are extremely bright with a good cutoff. They are also DOT approved.
 

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...I do NOT know why this would have to be...old bulbed devices appeared to work as advertised independently. Any EEs out there who can explain?..
I'm no EE but a retired professional geek. The flasher system is designed for a specific resistance (the flasher itself I think also) and apparently the PCM isn't happy without the nominal resistance of the bulb circuit (two bulbs in case of the tail lights.) I would need to look at the specific circuitry to more fully understand what they're doing. Somebody out there must have done the legwork to fully describe the situation.
 

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for the rears, the LED relay works
for the fronts, you need a load resistor. I don't recall on which wires on the three wire front circuit. I experimented and found the answer years ago.
 

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I have LED’s on the front and couldn’t get LED’s To run on the rear. I finally just put the OEM bulbs back in the rear.
Going to have to revisit this project and try resistors in the front circuit.
 

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OK, I am a EE, but converted to IT Project Management about 20 years ago. The challenge with working with LEDs is that most folks understand voltage - i.e. higher voltage, brighter light. However, the LED is a light emitting diode, which is a current device. It is made of a little piece of silicon with a doping material, like gallium added. When a current passes through it, it emits photons, or light. Put a bunch of them together and you get a tail light. They almost always include, in the housing, a current limiting device, often a resistor, to prevent too much current flowing in the event of a short, water, etc. Raising or lower the voltage doesn't affect these, unless by doing so you reduce the current below the amount needed to activate the diodes. I suspect, but don't know, that the PCM is looking for a voltage drop when the light is on, because it was designed around 12VDC incandescent lamps. The manufacturers of the replacement LED tail lights must put in circuitry to fool the PCM into thinking the voltage is dropping when the light is on. One of the issues is how little current is actually needed to activate the LED. A single LED lights brightly at 20mA. That's 20/1000 of one amp. If there are 50 LEDs in the housing, then 50 x 20 is 1000, so the total current is 1000/1000 A or 1 A. That's about half of what a single filament 12VDC lamp draws. Also, about 85% of the energy that goes into an incandescent lamp is released as heat, shortening the life time of the bulb. LEDs run very cool and nearly 100% of the energy is light.
Thanks for taking me back to 1978 when we were just starting to use LEDs in electronics equipment and nobody knew how to make them work correctly!
 

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Great explanation, thanks. I was around when #47 bulbs were used for dial lights and then the transition to LEDs. Always had a bunch of fun burning the LEDs up (it's a geek thing :smile:.)
 
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