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Do you know why these 2 pins in this autoharness are connected?

Discussion in 'Gen 3 Prius Technical Discussion' started by afshin, Apr 19, 2024.

  1. afshin

    afshin New Member

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    Hi All,

    I have a Japan Prius 2015 (3rd gen). When I bought the car, seller installed an after market nav for me, but it is not a very good device. So I decided to buy a new good one and I have bought a DHM-W4660NEX. SInce the connection is complex, I also bought an harness cable from autoharnesshouse which supposed to work for pioneer and non-JBL toyota (I assume my car is non-JBL because I don't see any fancy audio system around, but I'm not 100% sure). Anyway, after receiving the cable I thought it is better to check it before using it. Harness image is attached:
    harness.png
    I tried to compare connection with electrical wiring diagrams that I found in internet (To be frank, I'm not 100% sure that these diagrams match my device or not). From what I understand, most cabled are connected correctly. There is only 1 connection that I don't understand correctly and it is the loop that I marked in the picture and connects pin 8 and 9 together. From what I see, 9 is should be power amp and 8 should be antenna and I don't know why they are connected in this cable. Any idea?
    The second problem is vehicle speed signal and e-brake signal. Does prius 2015 have those signal?
    My final question is that is it a good idea to use a cable like this at all or not? Sadly, It seems I cannot get my steering wheel buttons work directly and I needed something extra like maestro rr or sw. Do you think additional features from maestro rr justifies its price or not?

    Best Regards
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Maybe so that one blue wire can fire up a separate amplifier and put up an antenna if that was a thing The amplifier could be a thing the antenna we don't have unless our antenna uses power for some sort of an amplifier for the antenna signal which is possible so I wouldn't mess with that that should be okay some cheaper m e t r a stereo harnesses I believe are similar that shouldn't really cause you any strife I guess if one wanted to you could cut that loop and tap onto that say if you had a power amp but our antenna is in fact non amplified then again it probably won't go anywhere on the car side if it doesn't need to so with our antenna is in fact amplified it would need the power. If it's not then it shouldn't need the power because it doesn't lower and raise electronically. If you don't have an outboard amplifier from your existing stereo like with the JBL system then that blue power wire for the amplifier probably does nothing in this situation so with this harness I guess you could add an amplifier and have a place to tap in to pick up power when you put the stereo on I remember a little bit of this just from installing stereos on various vehicles from the '70s through the late '90s buying devices to make your steering wheel buttons work the value to that can only be set by you and your mind to me it wouldn't be worth it I don't ever use the steering wheel buttons like never I will never stop reaching for a knob to turn up the volume even my stereos at home all have volume knobs even if they have a remote I rarely use the remote the knob for the integrated amplifier or whatever is right near my hand what I'm sitting My stereo is not hidden in the closet 30 ft away I'd rather not hunt for remotes. Driving doesn't take so much of my attention that I can't turn the volume up when it does then I probably won't be listening to the stereo that much. I have turned the air conditioning on once or twice in my time with the Prius via the steering wheel buttons but then it's in auto mode and I don't like it in that mode so I have to reach over to the MFD to put it in low manual medium fan.
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    That Pioneer deck won't accept steering wheel controls from a Prius unless you use an adapter box in the middle.

    I'm sure there is a Maestro box to do that, but there is probably a cheaper Axxess box available.

    The 2015 Prius has both vehicle speed pulse and parking brake status wires. I don't know which ones they are in yours- our car is a different model.

    Regarding your wiring harness- are you saying that the power amp output from the Pioneer is wired to the antenna power line on the car harness? That may be appropriate; many Toyotas require a 12v feed from the head unit to operate an RF pre-amp closer to the actual radio antenna. When using an aftermarket head unit, you generally use the "blue power amp wire" to feed that circuit.
     
  4. afshin

    afshin New Member

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    Thanks a lot for the info.
    I have not tried installing head-unit yet, but I decided to open and see what's going on in the behind.
    I noticed that in similar jack pin 9 was not connected and I'm personally not too sure about that pin as well. So if I noticed that pin 9 is really connected to somewhere in the car side, I try to dislocate pin 9 of my harness (not cut, just dislocate) and try the cable without connecting pin 8 and 9 together first and see how things are working. If I noticed something abnormal, I will then try both pins.

    Regarding steering wheel control, I really wonder if we need those adapter boxes. I saw this video today:

    It is a 2007 prius and head unit is a sony as well, so I'm not sure if it really works or not. But there are other similar videos with pioneer head units but different cars as well.
     
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I've heard some head units had some ability to work directly, but I haven't investigated lately. It's been 6 years since I bought a new head unit. Very good news if it's true!