Taillight LED bulb question

4690 Views 18 Replies 6 Participants Last post by ChevyGuy, Jan 5, 2016

izzone2000

Discussion Starter · Dec 26, 2015 (Edited)

So I installed new LED bulbs in my taillights a few days ago, and noticed that the two interior trunk lights are always fully lit as if the brakes were on. Anyone who installed LED's in their tails have this happen, and find a solution? Thanks

Automotive lighting Headlamp Light Lighting Vehicle

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Robby

· #2 · Dec 27, 2015

Your photo didn't come through but I think you are asking about the two red lamps in the trunk lid.

They are on as running lights anytime the park or headlamps are on........same intensity as the outer red lamps.
The outer red lamp are the only ones that have the brake lamp circuit enabled....the inner lamp intensity stays the same.

The brake lamp circuit is independent of the wiring for the red lamps in the trunk lid........put a stock bulb on one side and compare.

Rob

ChevyGuy

· #3 · Dec 27, 2015

Make sure you put the right kind of bulb in there. The lights on the trunk lid are only tail lights - they are not brake lights. So you should see them light up at tail light brightness - but never at brake light intensity.

LiveTrash

· #4 · Dec 27, 2015

I found when I put LED bulbs in my tail lights the difference in brightness between running lights and braking lights was very close together and it was hard to tell if the brakes were on or not at night.

I actually took a video comparison shot of the LEDs I had installed. I put in brake lights, turn signals and reverse lights. I returned all of them but the reverse lights. I found the turn signals weren't nearly bright enough to be seen during the day. Here's the video: https://www.youtube.com/watch?v=d5VN1uJLVTg Right tail light has the LEDs. Left tail light has stock bulbs.

izzone2000

Discussion Starter · #5 · Dec 27, 2015

Sorry. Original post updated with a working picture. All four lights are using morimoto xb led 3157 bulbs. When I press the brake pedal, the two outer lights become the same intensity as the two inner lights.

Robby

· #6 · Dec 27, 2015 (Edited)

Remove and re-install the inner bulbs 180 degrees from their current position.

The factory used 3157 bulbs in the inner and outer positions, likely for cost control and assembly ease.
3157 are a dual wattage bulb.....low side is running/high side is brake........the inners are using (and powering) the low wattage side only and I'm thinking may be install directional when a LED is in place.
So, by flipping the bulb 180 degrees in the connector you will power the low wattage side on the LED.

Otherwise, you can go to a 3156 type LED......a single wattage (should match the low wattage or lumen rating of your 3157 type) bulb.

Best guess from me,
Rob

Edit: Thinking further.....forget the 1156 idea....It'll be too bright.......do the 180 degree flip and report back.

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izzone2000

Discussion Starter · #7 · Dec 31, 2015

Thanks for the suggestion Rob. Unfortunately, after flipping the bulb 180 degrees, the LED's refused to even turn on. So, I'll be going back to the original 3056 dual filaments that came with the tails and getting a refund for the LED's.

evo77

· #8 · Dec 31, 2015

There should be no reason to upgrade the bulbs on the trunk lid to leds unless you plan to convert them to brake function. Otherwise it's just a waste of money.

In fact I removed the trunk lid bulbs entirely. Mainly because I wanted a slightly different look at night but also because they serve no other purpose but to be used as an extra pair of parking lights.

The Morimoto led bulbs are an inadequate replacement over stock. There are better leds on the market. I am currently using a pair of bulbs that use 4 rear facing and 2 front facing (behind projector lense) Cree XB-D emitters. They draw 5.6w under brake mode and are just insanely bright.

Prior to swapping in these Cree bulbs I was using Philips Vision leds. The Philips leds were equal in intensity to the stock incandescents.
Here is a comparison in daylight. Philips left vs Cree right...

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evo77

· #9 · Dec 31, 2015

LiveTrash said:
I found when I put LED bulbs in my tail lights the difference in brightness between running lights and braking lights was very close together and it was hard to tell if the brakes were on or not at night.

This is a common issue among all led bulbs. The Chinese manufacturers just don't drop the input power on the tail low enough. The Cree bulbs I'm using draw 1w on the tail side. That's still too high. They need to be at least .5w. So to remedy this I purchased the PWM dimmer from Diode Dynamics and here is what I got...

Before dim and then after dim.

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ChevyGuy

· #10 · Jan 3, 2016

izzone2000 said:
So I installed new LED bulbs in my taillights a few days ago, and noticed that the two interior trunk lights are always fully lit as if the brakes were on.

I did the same and run into the same problem. I think I know what it is, but have to do some testing. I think a socket modification is called for.

evo77 said:
There should be no reason to upgrade the bulbs on the trunk lid to leds unless you plan to convert them to brake function. Otherwise it's just a waste of money.

Depends on what you're looking for. With the brake lights converted, the trunk lights are now look orange. Those need to be changed to maintain a uniform color.

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ChevyGuy

· #11 · Jan 3, 2016

OK, I figured out what's going on. The "hot" side is connected to both "filaments", but the ground side is only connected to the desired one. Not a problem for normal bulbs, but the LED light drivers were designed for "hot switched", not "ground switched". Since both filaments are "hot", it goes into "brake" mode.

Once I figured out what was going on, a bit of electrical tape over the offending pin fixed it.

izzone2000

Discussion Starter · #12 · Jan 4, 2016

Cool. Thank you for taking the time to figure that out. I think for right now I'll be staying with the original bulbs until they burn out. The LED's just made the lights look washed out, too orangey for me.

ChevyGuy

· #13 · Jan 4, 2016

izzone2000 said:
The LED's just made the lights look washed out, too orangey for me.

You probably installed white LEDs. I ran into the same problem when I tried to do my side-lights. Bright, yes, but the front side light went from a nice amber to the color of lemonade. Lesson learned: buy the LED in the color that you want the light to be.

For my taillights, I installed some red ones. No washout there. If anything it's less orangey than stock.

Reactions: 1

izzone2000

Discussion Starter · #14 · Jan 4, 2016

ChevyGuy said:
You probably installed white LEDs

Yeah, all white. Where did you purchase your red ones?

ChevyGuy

· #15 · Jan 4, 2016

I used the forum vendor Diode Dynamics. I picked up two sets of the HP11. I like them for the brake light, but I am considering on switching the trunk lights to HP48. I hope to do a write-up with photos sometime this next weekend.

Free shipping for forum members.

I also installed a pair of HP36 for the backup lights. I need to do a little more testing, but it's in improvement. It's a bit weird, the OEM is brighter in that it focuses the light, but it's not usable. So the more even unfocused light works better.

AutumnCruzeRS

· #16 · Jan 5, 2016

I went back to stock on the outer bulbs and left the inner trunk lights with the LEDs. The inners now give the look of those luxury euro cars with the rear fog lights. The difference in the running and braking wasnt enough for me on the outers with LEDs.

ChevyGuy

· #17 · Jan 5, 2016

AutumnCruzeRS said:
The difference in the running and braking wasnt enough for me on the outers with LEDs.

Trust me, no problem with the HP11. I press the brake and the world behind me turns red. They're supposedly only a little brighter than OEM.

evo77

· #18 · Jan 5, 2016

HP11 has nothing on the bulbs I posted above (dubbed 30w Cree XB on the market). Our round reflector housings really suit the design of this bulb well since the emitters fire directly backwards. Unlike most other bulbs that fire directly out to the side and forward.

They are truly death lazers from behind. And they will light up signs behind you an eighth mile back, lol.

They do NOT however work good in the rear turn signal housing. I've got the mighty Vleds Tritons in there which dominates all.

ChevyGuy

· #19 · Jan 5, 2016

evo77 said:
HP11 has nothing on the bulbs I posted above (dubbed 30w Cree XB on the market). Our round reflector housings really suit the design of this bulb well since the emitters fire directly backwards. Unlike most other bulbs that fire directly out to the side and forward.

They are truly death lazers from behind. And they will light up signs behind you an eighth mile back, lol.

That's nice, but it's not my aim to blind people behind me. A little brighter is nice. But the poster was complaining about LEDs were the brake mode wasn't that much brighter. No problem with the HP11. There is a very definite difference between tail and brake.

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