10

I've noticed in several new vehicles the following scenario:

  1. Vehicle is traveling with LED day-time running lights around/adjacent to the headlights
  2. Vehicle activates turn signal indicator
  3. Vehicle shuts off LED running light while turn signal indicator is flashing
  4. LED running lights turn on once the turn signal indicator stops

Here are the cars I've seen seen this happen:

  • Jeep Grand Cherokee
  • Audi Q5
  • Kia Sportage
  • Ford Focus

Why don't the LED running lights stay on while the turn signal is on?

3
  • 1
    I am an automotive engineer and I don't like this feature either. It is very gimmicky and distracting.
    – Andy
    Commented Jan 31, 2017 at 9:38
  • They are not running lights, they are purely decorative.
    – vini_i
    Commented Jan 31, 2017 at 13:58
  • Vini - no. These cars do specifically have them as running lights. Not decorative.
    – Rory Alsop
    Commented Apr 6, 2017 at 8:35

3 Answers 3

16

The main purpose for this is so other drivers can see your turn signal. The LED lights are so intense, they do not allow the oncoming driver to be able to see the turn signal. By turning the LEDs off, it becomes readily apparent.

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  • 1
    Makes perfect sense. I suppose the part I left out that lead to my confusion is that I've seen cars with halogen running lights stay on while the turn signal is in use, but your point of the brightness of LEDs explains the difference.
    – Trevor D
    Commented Aug 26, 2015 at 18:07
  • 3
    Yes, and: I'm not sure if it's the same everywhere. But more expensive cars here just dim the LEDs, and this only on the side where the turn signal is on, while those on the other side remain bright.
    – sweber
    Commented Jan 15, 2016 at 7:54
  • This reasoning makes sense, but in practice I've been finding it more distracting than helpful. Perhaps it's the abrupt change in brightness / visual balance. Perhaps it's because I immediately think "electrical issues?" when I glance in a mirror and see one DLR and no ambers (cough GM trucks). Still, OEM LED lighting still feels stylistically very young. It'll be interesting to see if this trend evolves or dies.
    – zourtney
    Commented Jan 15, 2016 at 22:47
  • I believe that the regulations regarding DRL's state that they "may" switch off one side whilst the turn signal is in operation. The key being "may" because some manufacturers implement it and some don't. It also appears to be year dependent and it wouldn't surprise me if it could be coded in / coded out in the cars configuration. Commented Oct 4, 2016 at 11:20
  • 1
    @TrevorD - So, pretty much what I said? Thanks for showing us the "regulatory" reason! Definitely adds to the answer. Commented Feb 16, 2017 at 21:49
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I've read in this blog that if you place the DRLs away from the turn signal, then you would not need to turn of the DRLs when turning. I agree with this approach. Cars lose a lot of style points when they seem lopsided with one part of the DRLs turned off.

In fact there are many cars that do not have this issue.

I would go one step further and say that it is lazy or poor design. Take your pick.

-1

It is distracting and I believe it's a safety issue due to bad design. It's easy to design a light that has the led daytime driving light in another location that still allows the turn signal to perform properly. I have already seen many new cars with LED daytime running lights that do not require the light to turn off, to see the turn signal.

Call it what it is. Bad design.

1
  • maybe you could only notice the indicator with DRLs during daytime because it is "distracting"
    – Nilabja
    Commented Aug 24, 2017 at 10:34

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