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Replacing Turn Signal Relay after LED Upgrades - See Where The Relay Is Located - Gen2 (2004-2009)

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ODIOUS, Jan 10, 2019.

  1. ODIOUS

    ODIOUS Junior Member

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    2005 Prius
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    Two
    So I went ahead and swapped out the front turn signal bulbs and replaced them with LEDs (7440). Bcos I knew I they would hyperflash I purchased a pair of Morimoto LED Load Resistor (Part # LED420 from The Retrofit Source) for $7.50 a pop. I installed 2 up front and said I would do the back a little later. After doing some more reading I discovered that there is a single plug and play relay what solves the hyperflash issue for all the turn signal bulbs and it even compatible with incandescent bulbs. It just so happens that the Hyperflash Relay (Part# CF18 / LM449 from The Retrofit Source) is only $10 while it would cost $30 to do all 4 corners of the car with the load resistors. Seemed like a no brainer but after some more research I discovered that the install was a back breaking task but I really had nothing to lose so I went for it.

    First thing I discovered was, of the few pictures and videos i could find, none of them were from the Gen2. Just the new models. Most threads assumed that that location of the relay would be similar and thus the install would go about the same way but that was not the case. One post in particular (post #11) by Priusmpg entitled "LED Turn Signal Relay/Flasher" had a few great pictures and I dove in expecting to see what Priusmpg saw. But after a few minutes I was getting frustrated bcos I could not find it. (sorry I will post a hyperlink when my account ages a bit).

    I read somewhere that you could/should activate the turn signal so you can hear and feel the relay working. This will help you locate it quickly. I did just that and put my hands up in the area where the pictures indicated the relay would be but, even though I could hear it working, I felt nothing. So I followed the sound and discovered that the relay was on the fuse box under the dash (right in front of the break pedal). Much easier to access than in preceding generations.

    [​IMG]

    Below is a picture of the relay pulled out but still in its spot where it actually goes on the fuse box.
    [​IMG]
    The only issue you have to contend with is a small metal plate which so happens to be right over the relay when the fuse box is in its normal position but you can tilt the fuse box back (using a screwdriver for leverage) just enough to get the really out. You can also use a screwdriver to leverage the relay out of its seated position too. Its better to remove the bottom part of the dashboard for easier access but I completed the job by simply removing a single screw and pulling it back.

    Now the new relay will come with an adjustable knob on the top so can set blink rate (faster or slower) to you desired taste. This knob protrudes from the main fuse and will rest on the metal plate but not to the point where it will be an issue.

    [​IMG]

    The relay will also likely come with 2 prongs on the side which are not needed and intact will prevent it the relay from sitting properly and making contact. Simply snip them off and you will be good to go.

    [​IMG]
    After I adjusted the flash rate I tidied everything back up and that was that.
    I hope this post and pics helped.
     
    #1 ODIOUS, Jan 10, 2019
    Last edited: Jan 10, 2019
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    What a wonderful first post :)

    And an excellent 'how-to', with detailed pictures (y)

    Question: I was under the impression you could buy LED bulbs with the load resisters built in now?
     
  3. ODIOUS

    ODIOUS Junior Member

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    Thank you for the compliment SFO. Ive been a long time reader and am glad I could finally give something back.
    Yes you are right. There are LEDs with built in load resisters but they are usually those smaller auxillary bulbs. Larger bulbs like the 7440 in our turn signals require a larger resistor. So large that they can't realistically be built into the bulb. So we have to go with the large external resistors which get really hot (from what Ive heard). Not only that the large resistor's wasting of power (turning current into heat) goes against one of the main benefits of going with LED. So changing the relay is the best way to go if hyper flashing even bothers you.
     
    SFO likes this.
  4. netsplit

    netsplit Junior Member

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    Signed up just to thank you for this! Changing the relay on mine and this made it really easy to find it. I already the bottom part of the dash open, and I just took the metal plate off. It was held on by 3 10mm (of course) bolts.

    A lot of other guides I found suggested the relay was in several different places, none of which it was so again your guide was a big help. Thank you!
     
    SFO likes this.
  5. Another

    Another Senior Member

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  6. ccwcsax

    ccwcsax New Member

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    Good tip. Worked for 2009 Prius. Dropped the bottom half of the dash, took off the three 10mm nuts, clipped the tabs off the new relay and swapped for the old hyper-flashing original relay. Normal flashing with LED bulbs.
     
    netsplit likes this.
  7. Traction2077

    Traction2077 New Member

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  8. Traction2077

    Traction2077 New Member

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    Thanks to this post I replaced the relay with an adjustable one to address hyperflashing after brake lights were replaced with LEDs. The metal plate mentioned can be removed by removing 3 10mm nuts once the lower dash is removed. Not too hard.

    To remove lower dash remove visible screw in the center of lower dash, remove left vent surround by pulling straight out, now remove another screw in lower dash which will now be visible. After this gently loosen lower dash and it will come out (can optionally unplug two wire harnesses to remove lower dash completely) and metal plate can then be removed by removing three 10mm nuts. This made replacing the blinker relay much, much easier.

    I had never taken any part of the dash off and I was able to do so without breaking anything. I count that as a win!
     
    netsplit likes this.
  9. Sand Hurst

    Sand Hurst Junior Member

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    I inherited Amber LED's bulbs on a used 2007 prius purchased last August. During a long wait for left turn, (after about two or three Consecutive red signals switches), it hyper-flashed. HAZ fuse blew. None of the turn signal lights nor the dash indicators worked. Replaced fuse and it blew as well. Replaced 81980-46010 with LED 81980-50030 flasher from Amazon and fuse, it did not work. Checked HAZ wiring at MFD and instruments fuse under steering wheel, attempted another two flashers 81980-46010 and 81980-50030, it did not work for me. The wiring was testing clear to me all along.

    In short after burning 5 HAZ fuses under the hood and attempting 3 replacement flashers over a month or so, I down graded to Halogen bulbs. In first attempt, it worked with original factory flasher that was originally suspected. The short circuit was inside the LED bulbs. Returned the three replacement flashers. Neither the after-market 81980-46010 nor the two after market 81980-50030 flashers worked with both Halogens nor faulty LED's.

    Long hyper flash would have only damaged left side bulbs, why right side signal and instrument cluster on-dash indicator green arrow lights also stopped working - no clue.

    Moral of the story: Stay away from LED turn signal bulbs.
     
    #9 Sand Hurst, Oct 25, 2023
    Last edited: Oct 25, 2023