Success! 2018 Head Unit replaced with 2021 Head unit with Carplay!

Discussion in 'Gen 4 Prius Audio and Electronics' started by Bkleini, Apr 17, 2022.

  1. Bkleini

    Bkleini Junior Member

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    Hello everyone! Id' thought id share that it IS possible to upgrade a pre-facelift gen 4 radio with a Pioneer/Denso unit that supports Apple Carplay along with Android Auto while keeping other functionalities! I'm planning on making a guide soon (I'm a busy college student) but here are some pictures I took!

    Old Headunit: Panasonic base headunit (found in 2018 Prius Two):
    Model Number: 86140-47271
    20220417_114341.jpg 20220417_114350.jpg



    New Head unit:
    Model Number 86140-47710
    from a salvaged 2021 Toyota Prius Prime LE (TRIM LEVEL IS IMPORTANT!!). - paid $300
    new connectors.jpg

    You will notice that the connectors are very different from each other, but I decided to take the risk and create my own harness. Again, I will write up a complete guide once school is out.

    and finally, here is some pictures of the installed unit in my vehicle!
    20220417_105121 (1).jpg
    20220416_231554 - Copy.jpg


    Finally, Here are the functions I have checked and are working:
    -Vehicle Customization (all settings on old are on the new head unit, though it took a few days to appear)
    -Energy monitor (the battery level does not show, but everything else shows, including power flow to the HVAC, did not have that before)
    -Factory USB plug (Data and power)
    -All Steering wheel controls
    -Reverse Cam
    -AM/FM (the only plug that stayed the same!!)
    -Android Auto
    -MPG display works

    Things that do not work:
    -AUX IN (I'm sure if you got a head unit that supported aux, it would work but 2021 prime does not have a AUX jack)
    -The radio option in the MID did not appear
    -Any of the DCM/Telematics functions that were in this radio

    Not tested:
    -Apple Carplay (though i do not foresee any issues coming up)
    -Communication with Toyota Techstream.

    That's all I have for now! please feel free to ask questions!!
     
  2. bisco

    bisco cookie crumbler

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    well done, thanks for the write up!(y)
     
  3. matthew042

    matthew042 Junior Member

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    Thanks for the writeup, Bkleini!

    I'm most curious how you created the custom wire-harness... I've always wanted to tackle this project, but the uncertainty of not knowing which wires went where prevented me from doing so.

    And curious why you chose Prius Prime headunit over a regular Prius headunit? Won't the prime headunit display irrelevant info? Did you ever consider the regular Prius headunit?

    I do know that starting with the 2020 mode years, Prime headunit kept the disc player, while the regular Prius did without it.
     
  4. Kragzakh

    Kragzakh Junior Member

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    Awesome job! I’m curious if this is possible with the 11” screen version? I really want to do this with my ‘17 Prime.
     
  5. Bkleini

    Bkleini Junior Member

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    Hey there, the harness creation took the longest. Basically, I went on to get Access to Toyota's TIS system, and wrote down all the signal wires going into the old harness then the new one, and made a splice (using connectors and pins to make a so called T-harness) between the connections. id say %95 of the wires had similar names that were easy to pair up with the new one. and the ones that did confuse me (telematics especially) I left disconnected and everything worked fine! I chose the prime headunit becase it was the only one i could find at the time that i knew for a fact had AA and that was within my price point.

    The base prime headunit didn't have much irrelevant info, the only thing i could find on the radio that alluded to the prime was on the energy flow screen, where there was a "path" going outside of the vehicle from the battery, but its very small and i dont notice it honestly. I think this is due to the fact that the base prime has all the charging settings up in the MID rather than the infotainment system. This unit does have the CD changer, which i suppose sacrificed some screen size, but the price was right.
     
  6. Bkleini

    Bkleini Junior Member

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    Thank you! I cant guarantee anything, but if you already have the 17' display and want to put in a new 17" display, I am willing to bet you could do it making a wiring adapter like i did with my base model. the connectors on the back of the new 17" seemed to be the same on my new DENSO unit. I would double check the climate control wiring as well.

    However, I'm not sure on upgrading a normal (double din size) to the 17" size. the vents might require different dashboard parts along with mounting points. id welcome someone to do some research into this and maybe someone has done it!
     
  7. IHasBirbs

    IHasBirbs Junior Member

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    Hey, so are you going to post the guide? I also have a few other questions...

    for trim level, do you have to get the head unit from the equivalent of your trim (i.e. Four->Ltd.)
    Did you end up testing the apple carplay and techstream?

    Also, i think telematics is only for safety connect?
     
  8. Bkleini

    Bkleini Junior Member

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    Hi there, I still haven't gotten around to a guide but i can answer your questions:
    For the trim level, you need to make sure that you get the low trip Prime radio so it fits the cavity of the 18 prius. so matching the radio form factor is important.

    Apple Carplay works great, no issues

    Techstream is a bit odd, the only error this new radio will throw is an instrument cluster warning that communication is not established with the radio, but this doesn't seem to cause any other noticeable difference. Ill also note the mute function during PCS events still functions just fine, so there is definitely comms between ECUS

    If you need to communicate with the radio on techstream, simply tell techstream you are communicating with a 2021 prime, and you will then be able to access all radio functions

    As for Telematics, my vehicle did not have the SOS button, so i would not be able to make a guess if the new telematics still works
     
  9. Patric88

    Patric88 Junior Member

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    @Bkleini
    Can you post your notes or diagrams on the pin out? I want to do this ASAP. Came to the site looking for a radio improvement just like this.
     
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