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 New Member

    Joined:
    Jan 10, 2019
    3
    2
    0
    Location:
    Hell's Garage
    Vehicle:
    2005 Prius
    Model:
    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
    SFO likes this.
  2. SFO

    SFO Senior Member

    Joined:
    Feb 7, 2017
    1,243
    1,355
    0
    Location:
    Northern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    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 New Member

    Joined:
    Jan 10, 2019
    3
    2
    0
    Location:
    Hell's Garage
    Vehicle:
    2005 Prius
    Model:
    Two
    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.
Loading...