Denny Swift

A couple of years ago I started noticing that nearly every other car on the road seems to a burned out headlight. I couldn’t figure it out. Then I realized that it was a new feature! For some reason manufacturers started programming the lights so one of the DRLs would extinguish when the turn signal was activated. I was sitting at a red signal this morning looking at the opposing traffic waiting to turn and thought how silly and wrong they look with only one headlight on. Then I thought, hmmm, I hope my car doesn’t do that and realized I never looked! I looked. Thankfully, our cars don’t do that. I’m sure glad it’s not mandated. It looks so stupid to me.

tigerhonaker

Thanks for sharing ..........
I sure hope my GT4 doesn't do that.

Terry

Last_935

My understanding is that it is mandated and has to do with the proximity of the turn signal to the DRL. If they are in close proximity than the DRL has to turn off while the turn signal is activated. If that is not the case, I'm sure someone will chime in.

TikiLou

That was always my observation, too (although I don't know if it's mandated).

Alpha Ice

You are 100% correct. It has to be a certain distance from the headlight if on, so that with the light one one could distinguish that the turn signal was lit up while the lights are on. I believe most manufacturers probably don't want to make the light housings as large or big, unless you're Jeep with their headlight design on the Cherokees and trail hawks 🤯

I read about it on another forum previously as I thought too it was silly. I'm never outside my car with the lights and turn signal on haha.

LZRD GRN

It started in Europe about 10 yr ago, I recall Spanish Audis had this "feature"

Denny Swift

I’m not following. In all my cars, the turn signal is immediately adjacent to the DRL, yet the light stays on when the turn signal is activated. I think it’s just something that some manufacturers decided to do. I don’t think there is any mandate.

StormRune

Last_935 and others are correct that ot is due to a government mandate in certain circumstances.

See: https://www.govinfo.gov/content/pkg/...sec571-108.xml
Section S5.5.11(a)

Keys phases are:
"If optically combined with a turn signal lamp, is automatically deactivated as a DRL when the turn signal lamp or hazard warning lamp is activated, and automatically reactivated as a DRL when the turn signal lamp or hazard warning lamp is deactivated."
"If not optically combined with a turn signal lamp, is located so that the distance from its lighted edge to the optical center of the nearest turn signal lamp is not less than 100 mm, unless:(i) The luminous intensity of the DRL is not more than 2,600 candela at any location in the beam and the turn signal meets the requirements of S5.3.1.7;"