Low beam DRL mod completed

Discussion in 'Gen 2 Prius Audio and Electronics' started by prius_chatter, Jul 18, 2021.

  1. prius_chatter

    prius_chatter New Member

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    I am headed for Quebec soon and I believe:
    1. Canada won't approve of my car unless it has "daytime running lights" (DRL).
    2. If the low beams come on whenever the car is on, this counts as DRL.
    So, I modified the headlights to be on whenever IG-ON.

    The OEM DRL option (not available on US models) brings the low beams on at reduced intensity. This is orchestrated by the body ECU and involves a component (which is not a relay) called "Daytime Running Light Relay" at D2 on Instrument Panel Wire. If I were staying in Canada longer, I would want to replicate this setup on my Gen2, but my mod (forcing the headlights on at full intensity) was easier and works well enough.

    On any Gen2, the headlights are activated by closing the H-LP relay located in the engine room relay block, which the Body ECU does by pulling its HRLY line low. I added a 4-pin relay with the contacts connected between HRLY and ground and the coil connected between ignition power (GAUGE circuit) and ground.

    I chose to tap
    • HRLY at inter-harness connector IJ3,
    • GAUGE at junction connector J10 (pins E), and
    • ground at grounding junction connector J5.
    IJ3 is located inside the dashboard on the far right side and easy to access after removing the glove box. J10 and J5 are located only inches away from IJ3 but slightly harder to access. J10 is taped to its harness (Engine Room Main Wire) above the passenger kick panel. J5 is bolted to the chassis wall beside the HV ECU.

    Rather than cutting and splicing harness wires, I moved and added connector terminals. Specifically, for HRLY, I removed terminal 2 on the Engine Room Main Wire side of IJ3, added a new terminal in its place, placed the terminal I removed from IJ3 into a new connector pair, and added a new terminal to the mating connector. To complete the HRLY tap, the new terminals' wires are crimped together (into a standard 1/4" quick-disconnect terminal, which receives the appropriate lead of the new relay.) For GAUGE and ground, I simply added new terminals in spare positions of the junction connectors. (And crimped more quick-disconnect terminals onto their wires.) Working with terminals is probably more laborious than splicing harness wires, but I find it extremely satisfying, and it makes my mod neatly reversible.

    I have a pile of extra Gen2 wiring harnesses from my parts car. Instead of buying new terminals, wire, and a connector pair, I cut what I needed off of those. It worked well for this small project, but I know that for future wiring mods, I will want to crimp my own terminals. I believe most terminal types used in Gen2, and some connectors, can be ordered in small quantities from hi-1000ec.com.

    My Gen2 has halogen headlights, not HIDs. I don't know if this mod would work with HIDs. If my car had HIDs, it would also have fog lights, and I would have modified those instead.
     
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  2. bisco

    bisco cookie crumbler

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    well done, and good luck with the move, sounds exciting!(y)
     
  3. ChapmanF

    ChapmanF Senior Member

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    If I'm not mistaken, the OEM option may work by bringing the high beams on at reduced intensity.

    That would give better daytime visibility, because those are the ones pointed more toward the other drivers' eyes.

    That's exactly why you need low beams at night (to avoid shining high beams into other drivers' night-adapted eyes), but in daytime, when their eyes are already adapted for daylight, and the intensity is cut for DRL use, that seems to be a common way DRL is done.)
     
  4. sam spade 2

    sam spade 2 Senior Member

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    Canada usually uses a good degree of common sense when making it's laws.......unlike their neighbor to the south. :eek:

    That probably means that if your car was legal in the country of origin at the time it was new, Canada will happily accept it too.
    But that is just a guess.

    I certainly would ASK before going to all that trouble.
     
  5. fuzzy1

    fuzzy1 Senior Member

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    A guess that has been proven wrong repeatedly in this forum, even since you joined.
    Previously asked, with answers contradicting your guess.
     
  6. sam spade 2

    sam spade 2 Senior Member

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    So ???
    And that is not necessarily true.
    The chart provided indicates that the year and model are important.
    Maybe that is because those required items WERE stock when the vehicles were new.

    But I am glad that you are still getting pleasure from giving me a hard time.
    Keep it coming. :whistle:
     
  7. ChapmanF

    ChapmanF Senior Member

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    From the second link given in #5:

    12. DAYTIME RUNNING LAMPS (CMVSS 108) - All passenger cars, multi-purpose passenger vehicles, trucks and buses imported into Canada must be equipped with functional daytime running lamps.
     
  8. fuzzy1

    fuzzy1 Senior Member

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    Examples please?

    Section 12, repeated above, appears to leave no such room.
    DRLs were mandated on all vehicles made or imported into Canada more than three decades ago. Admissible Prii need to have them added.

    Beyond that, a few listed Prii on that Toyota-model-year list are inadmissible because they lack a km/h scale option on the speedometer.
    Considering the considerable pleasure you appear to derive from continually giving, you may as well receive some too.
     
    #9 fuzzy1, Jul 19, 2021
    Last edited: Jul 19, 2021
  9. xliderider

    xliderider Senior Member

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    This $40 module/controller is made for the Gen 2 Prius, but has also been installed in Gen 3 and Prius v models as well.

    It uses the parking lights, but could probably be wired to use foglights (if available) as well, you wouldn't use wire it to indicate turn signaling, in that case.

    2004-2009 Toyota Prius DRL-2P Daytime Running Lights

    Posted via the PriusChat mobile app.
     
    #10 xliderider, Jul 19, 2021
    Last edited: Jul 19, 2021
  10. alftoy

    alftoy Active Member

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    I have a 2008 US import, has the speedo with button to show km or mph. Never noticed how the DRL were implemented.

    I also have a 2008 Tacoma US import. The previous owner had installed the Canadian Tire DRL kit. I happened to come across a thread on Tacomaworld suggesting that all that is required to enable DRL is to change to a DRL relay which I then installed and ripped out the Cdn Tire DRL kit. Curious if that would be the case with the Prius. Prius service manual shows a DRL relay.

    https://parts.olathetoyota.com/oem-parts/toyota-drl-relay-8281047030?c=Zz1lbGVjdHJpY2FsJnM9ZGF5dGltZS1ydW5uaW5nLWxhbXBzJmw9MSZuPUFzc2VtYmxpZXMgUGFnZSZhPXRveW90YSZvPXByaXVzJnk9MjAwOCZ0PWJhc2UmZT0xLTVsLWw0LWVsZWN0cmljLWdhcw%3D%3D
     

    Attached Files:

    #11 alftoy, Jul 23, 2021
    Last edited: Jul 23, 2021
  11. ChapmanF

    ChapmanF Senior Member

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    Looking in a 2006 Electrical Wiring Diagram (more info), there is a "Daytime Running Light Relay" and a "Diode (Daytime Running Light)", both located up in the instrument panel, and a "DRL NO. 4 RR FOG Relay", located in the "engine room relay block no. 2" under the hood, up by the windshield cowl. The wires to all these locations won't exist if the car was sold without DRLs.

    It's possible a 2007 wiring diagram would show something different, but I don't know how likely.

    Interestingly, because Gen 2 used dual-filament incandescent bulbs, the "daytime running light relay" does its pulse-modulation magic on the common ground side, so it would give a dimmed version of either the high or the low beams, depending on which way the DIM relay is switched. But the Body ECU controls that relay, and probably only switches it one way when the DRLs are on.

    Even if all those components and all the missing wires were added in an originally non-DRL car, it's not guaranteed that the version of the Body ECU in that car will have the programming to drive the right outputs.

    -----

    The situation for Gen 3 is equally frustrating. DRL versions come with a "DRL relay" that goes in the same place in the underhood fusebox where the "DIM relay" goes in non-DRL cars. The pinouts are different, so you can't just swap the relays; you have to get the other kind of socket and then mod the fusebox.

    [​IMG]

    Even then, there is uncertainty that the non-DRL body ECU version will pull down the right output to turn the thing on.
     
  12. alftoy

    alftoy Active Member

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    Have you traced physical wiring DRL vs no DRL to say for certain that wiring doesn't exist or are you suggesting.?

    Note service manual wiring diagram, shows same wiring with no DRL and a optional port for the under dash DRL relay on the same wire leg to the headlight.. Service mode shows option to turn on DRL.
     

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  13. ChapmanF

    ChapmanF Senior Member

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    You've only included one page of the "Headlight" system circuit diagram, and not the one that shows the Daytime Running Light Relay or the Diode (Daytime Running Light).

    Even the diagrams you have included have red highlighting added to show wiring differences between the *1 (with DRL) and *2 (without DRL) wire harness versions, though electrically those differences are inconsequential, as all that changes is whether the HRLY circuit passes through a junction connector or not. :)

    But if you turn the page and look at the diagram pages that actually show the Daytime Running Light Relay and the Diode, if you are looking in the same diagram edition I am, you will see that all of the wires connecting to those items are annotated *1 and therefore present only in DRL-enabled wire harnesses.
     
  14. alftoy

    alftoy Active Member

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    This is the 2nd Gen Tacoma page for Toyota parts to enable DRL. The module required is a flasher which I found at a salvage yard and the jumper I ordered from Toyota. So is the DRL enabled wire harness in the Prius also a jumper?

    DTRL Install DIY | Toyota Nation Forum
     
    #15 alftoy, Jul 24, 2021
    Last edited: Jul 24, 2021
  15. ChapmanF

    ChapmanF Senior Member

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    The approach used for DRL on Tacoma seems to be quite different from the approach in Prius, and even for Prius there have been significant differences between generations.

    If someone is interested in retrofitting DRL into a Tacoma, that Tacoma thread could be quite useful.

    If the goal is to retrofit a Gen 2 Prius, I've already described, in #12 and #14, what the 2006 Gen 2 Prius wiring diagram shows. If anyone is skeptical about getting that information second-hand from me (and that's fine with me, in fact I encourage it), or has a Gen 2 year other than 2006 and wants to make sure the details have or haven't changed for that year, the obvious step would be to follow the more info link and look first-hand at the circuit diagram for the model year of interest.
     
  16. Another

    Another Member

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    I wonder if the OP ever accomplished this?
     
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