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Mod to enable DRL

Discussion in 'Gen 4 Prius Accessories and Modifications' started by Silverstream, Oct 1, 2018.

  1. Silverstream

    Silverstream New Member

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    I've just collected my Prius and noticed that the DRL only lights up with the Fog light rather than staying permenantly on.

    I've seen other Prius with DRL, thus wondering if there's an easy way to turn on the DRL or do I have to tap and modify the wiring harness?
     
  2. alanclarkeau

    alanclarkeau Senior Member

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    DRL should be on all the time the position is in AUTO or "O" (while the car is Powered ON). I don't believe they come on with the Parking (position or side) lights, nor with Headlights or Fog Lights.

    upload_2018-10-2_16-4-7.png

    Read your Manual and check the settings. The Australian Manual gives the below - (but the USA switch is different):
    upload_2018-10-2_15-59-46.png
     
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  3. The Professor

    The Professor Senior Member

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    I can't speak for anywhere other than the UK market (what are they meant to do in Asia?), but DRLs here have to be on, by law, during the day when the car is moving. Some cars simplify this to simply having DRLs on whenever the headlights are off. The Gen 4 Prius is a bit more clever than that.

    It works exactly as shown in alanclarkeau's screenshot above. Auto means when it's daylight DRLs are on. When it's night Headlights only are on. The main difference here in the UK is there is no Position 4.

    If you choose position 2, DRLs are on (I think), along with very dim lights from above the headlight.

    If you choose position 3, DRLs are off and Headlights are on.

    It should also be noted that DRLs do not come on immediately. You must shift into D, B, or R. I'm not sure if you actually have to start moving too. But, once they're on, they will stay on, even when stopped, until either you switch the ignition off, or the Headlights come on (either Automatically or by selecting position 3). The best way to test them is to drive somewhere during the daytime, with Auto headlights on, and see if you can stop near a store glass window and see the reflection. Or get someone else to watch for you.

    And just for completeness, the DRLs are the vertical line of three LEDs towards the lowest point on the triangular looking fitting group of lights. The Fog lights are the horizontal set of LEDs towards the top of this triangular fitting.

    Here in the UK, the Fog lights don't affect the DRLs at all. Fog lights only work when the headlight selector is in Auto (Position 1) and it's dark, or in Position 2 or 3, but activating or deactivating the Fog lights doesn't turn on or off the DRLs.
     
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  4. Silverstream

    Silverstream New Member

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    Just tested mine, when it's AUTO, it'll light up in the evening with either the tiny parking light is ON or the main headlight is ON.

    When I manually turn it to "parking light", the 3 sets of DRL will switch on.

    There is no way to keep it permenantly on.
     
  5. The Professor

    The Professor Senior Member

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    Come to think of it... I don't think there's a combination where my fog lights are on at the same time as DRLs. It's always one, or the other, or neither.
     
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  6. Starship16

    Starship16 Senior Member

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    I don't know why, but I still don't completely trust that "Auto" mode for the DRLs and headlights. So I just turn them on/off manually each time I drive the car.

    And I wish more Gen4 Prius drivers would USE their DRL lights. We have those nice bright LEDs, but I keep seeing 2016-2018 regular Prius and Primes with no lights on. WHY???
     
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  7. The Professor

    The Professor Senior Member

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    I've found Auto headlights to be really good in all of the cars that I've had them in, apart from the very first (a Peugeot 206 around 15 years ago). Occasionally they come on when I don't think they're needed, but at least on the Prius you can adjust the sensitivity. I don't recall if that was a Carista/Dealership change, or if it's in the settings, but I made mine one level more sensitive. I feel that at the end of the day, it's better to be seen than not seen, or see than not see. They also react very quickly to tunnels, or thick tree cover, etc, and often help when I normally wouldn't bother to turn my lights on.

    Both the headlights and DRLs, whichever is on (I'm pretty sure they're mutually exclusive), are highly visible, so I wouldn't worry about having good lighting in Auto mode - you'll be seen.

    Try Auto! It works super well in my experience, and will prevent any chance of you forgetting to turn them on when they're needed.

    Auto High Beams on the other hand... I'm still on the fence. It's not perfect. They turn on a little late for my tastes (usually only a second or two, but it feels like a long time to be driving at 60 on country roads with normal headlights only). They also turn off a little late when they detect a vehicle - I get flashed quite often with Auto High Beams on. They also often get tricked by reflections, street lights, reflective things, signs, traffic lights, and so on, turning on and off far more frequently than I would.

    Auto Wipers... they're OK. I always use them by default, but again not perfect. If it's not your very typical rain they often turn on too late. Light misty type rain is especially bad. I find I've lost all visibility before the activate. But for the most part, I use them.

    Auto Gearbox? What are gears? ;)
     
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  8. alanclarkeau

    alanclarkeau Senior Member

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    Auto Wipers - yes, all the time;
    Auto Headlights - yes, all the time - apart from those grey, wet days when I want my headlights (and particularly tail-lights) on;
    Auto High Beam - only on more isolated roads - I don't like them if there's a lot of traffic around;
    FOG LIGHTS - like most these days on cars and sold as FOGLIGHTS, are next to USELESS - they're just a decorative gadget.

    Gears - they're the things which conventional car makers are putting more and more in their cars. I have no idea what $$$ it will cost to overhaul a 10 speed Mustang Auto (shared with GM) when it starts missing gears. Certainly makes HSD look more and more simple.
     
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  9. Starship16

    Starship16 Senior Member

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    I shouldn't say I don't "trust" the Auto settings. That's incorrect. I guess it's just force of habit to do everything manually. None of my previous cars had any Auto functions. I will start using it in my Prius and see how it works. I adjusted the headlight sensitivity to maximum. I'm curious to see how soon they come on. Thanks for the comments.
     
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  10. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    Maybe I am just too trusting, but I am perfectly happy with the "auto" settings. My car seems to have its lights on when necessary. I especially like the auto brights - they work as advertised.
     
  11. MagnusAG99

    MagnusAG99 Senior Member

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    I really dont see the problem of having the lights in Auto either, it annoys me so much that people dont put them in auto and drives with DRL at night for example. I see that everyday... How they dont understand they dont have their lights on amazes me, it doesnt light up squat and their taillights r off... Just blends on coming traffic like high beams. Whole point of DRL`s is to blend on coming traffic at daytime. Or the dudes that tries to act so damn cool and drives with foglights and parking lights at night...... When it comes to fogs i really dont see the point either... We r allowed to use them as DRL here, but there`s really no use for them other then that. When its fog they only light up the fog and blends u more also. Just a stupid gimmick really, i do love the fog lights that turns on when u turn tho, so the side gets illuminated a bit more when u turn. Even tho most cars have AFS now which turns the projectors in the main housing lol.

    But as for the problem this dude is having, i really dont understand how ur Fog`s, DRL`s and parking lights can come on at the same time? Pretty sure DRL`s r mandatory to be on alone in all countries...? Atleast here nothing else is allowed to be lit when the DRL`s r on, as soon as the main beams or parking lights or whatever comes on they have to turn off. Unless the DRL`s also is the parking lights and just dims down to like 40% to act as parking lights. But the prius DRL`s does not act as parking lights, so i really dont understand whats up with that car... Never heard of this before. Did u buy it used or did u buy it new? Im wondering if someone have messed around with the wiring to get it to look more "JDM" with lights all over the place...
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Auto headlights won't turn your headlights on, on a bleak rainy day? Am I right on that?

    I'm in the same camp as @Starship16: don't trust/like 'em, prefer manual. Also, it's clinically impossible for me to walk away from a car with the headlights blazing.
     
  13. MagnusAG99

    MagnusAG99 Senior Member

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    Some countries and some states in US have it as a law they have to auto turn on when its raining. But majority of countries dont, which i honestly find a little dumb..
     
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