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Questions on head unit replacement - Pioneer AVIC-8201

Discussion in 'Roadster 2008-2012' started by Carbuilder, May 27, 2019.

  1. Carbuilder

    Carbuilder Member

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    The Roadster I just bought had a double DIN Alpine INE-S920 head unit. Everything worked properly with it, but I had the Pioneer unit that I preferred. The Pioneer has Apple Car Play and a few other features I liked. So I swapped the unit in (makes it sound so easy!), and have a few issues with it.


    First, of course the wiring for the Roadster is difficult to figure out as it does not seem to use any conventional color-coding. Second, the unit had the Alpine “direct connect” backup camera which uses a 6-pin harness instead of the usual RCA plug. The GPS antenna uses a different plug, as does the microphone. So be prepared if you are going to do something like this to do a lot of head-scratching. The issues:


    As with any head unit, there is a lead for constant 12V and a lead for switched 12V (plus the ground of course). It took me hours to try and sort out why the wires from the car harness had the switched and constant 12V when measured, but the radio would not work when they were hooked up. It worked fine on the bench with a power supply hooked up. After a lot of measuring I found that the 12V constant power would drop to 2-3 volts when connected to the radio; why, I have no idea. If I jumpered across the 2 power supply leads then the radio worked fine. I didn’t know if this would do any harm but it seemed to work OK; and yes, it does power off when the car is shut down. The only issue is that when the car is started each time the radio is like it is booting up for the first time and goes through a couple of initial start-up screens, so this is not something I can live with. Is there something in the 12V constant power lead that is limited in some way? Can’t remember off-hand if it is the green or brown wire (1 is the constant power and the other is the switched). Is there another source for the 12V constant power I could try?


    Second issue. The camera itself works when “rear view” is selected on the radio, but does not go into it automatically when in reverse. I’ve got it set on the menus for “power” as opposed to “ground” for camera trigger, but tried both. Pretty sure I measured the leads and found the one that had 12V when in reverse and nothing (or very low voltage) when in drive. But I must have this one wrong somehow.


    The last issue is one that I’ve seen mentioned many times. How do you get the USB cable from the head unit to the rear of the console? I’ve searched and found bits and pieces of information on removing the console, but nothing that worked for me. I took the cover off the back of it (the traction control panel) and saw where the cable goes in. It would not pull out at all and seemed to come from the lower part of the console, not the upper part; when the console was loose at the back and I wiggled it the cable did not move. I took out a bunch of screws that I could see but nothing actually helped remove the console to see the cable run. I’ve seen it mentioned that the cable runs just under the transmission shift buttons, but like I said it seemed that mine was running under the lower part of the console. People putting in sound insulation must be removing the whole console, no?


    So if anyone has any suggestions for any of this feel free to post.

    thank you in advance,

    Rick
     
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  2. Rotarypower

    Rotarypower Member

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    Check out this thread...


    Surprisingly advanced Alpine unit

    I’ve posted wiring diagrams as well as others some useful reference material. I still have not replaced my original Alpine unit but will be doing so in the near future.

    Please keep us updated on your progress.
     
  3. Carbuilder

    Carbuilder Member

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    I've been playing around with trying to get this to work properly, without success so far.

    The issue seems to be that the constant 12 volt supply from the connector in the dash drops to around 8 volts when I hook up the radio, so the radio won't work.

    I hooked it up to the 12 volt accessory connection and it worked fine, but I think that one won't always be 12 volts (I think it turns off now and then so that will reset the radio).

    I tried it on the bench with a 12 volt supply and it worked fine. Unfortunately I don't have a meter that can measure DC current so I'm not sure how much it is drawing. But with it hooked up to a power supply or just the small 12V battery the voltage only dropped about .1V when it was hooked up and working.

    I thought it might be the small 12V battery so I replaced that; didn't make a difference. In fact, hooking the old battery up to the radio on the bench it worked fine.

    The small battery is around 13.5V. When I measure the voltage at the radio connection in the dash it is below 13V, so there is something strange going on. If it were a normal car I would just run a wire from the small battery to the back of the radio and use that as the constant 12V source, but I can't see any easy way to find a path for a wire.

    I found another unused 12V wire in the radio connector (it went into the connector in the dash, but the radio harness didn't have a pin to use it) and I tried connecting the radio to that one. Same thing......less than 13V to start and drops to 8V with the radio hooked up.

    With it connected to the accessory lead the radio worked fine, including the backup camera, so everything is connected OK, just a matter of finding a decent 12V constant supply that stays at 12V under a bit of load.

    Rick
     
  4. X.l.r.8

    X.l.r.8 Supporting Member

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    There’s a connector under there labeled APS. That’s probably best place to take your direct feed.
     
  5. Carbuilder

    Carbuilder Member

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    Where is it?
     
  6. Carbuilder

    Carbuilder Member

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    And does it have 12 volts when the car is asleep?
     
  7. X.l.r.8

    X.l.r.8 Supporting Member

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    Sorry, fell asleep looking for the link. It’s on a stereo thread where the talk was power for bigger amps. I’ll look for it later if you can’t find it.
     
  8. groovidad

    groovidad Living the Dream!

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    This is probably a “CPT Obvious” post but, obviously, something between the battery and the head unit is also drawing current (?). I’m know you said you’re having trouble finding a direct route from battery to head unit but, I believe that is your solution (?)
     
  9. X.l.r.8

    X.l.r.8 Supporting Member

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    What’s CPT?
     
  10. X.l.r.8

    X.l.r.8 Supporting Member

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    The battery is only a large capacitor for emergency systems. The fact you can drive quite happily without it shows it’s importance. The internal 12v system goes to sleep so you need either as mentioned above a 12v from the SLA, or a constant 12v which should be there from the previous original radio. It may take some poking around with a multi meter.
     
  11. ViperDoc

    ViperDoc Roadster 1305

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    I think the poster is using the abbreviation for “Captain” (eg, military title) so “Captain Obvious”
     
  12. X.l.r.8

    X.l.r.8 Supporting Member

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    Ahhh, not Compton then.
     
  13. Carbuilder

    Carbuilder Member

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    I’m using the 12v source from the previous radio, so I don’t know what is going on. I’ve found 2 different pins in the radio harness (the part in the car) and both are about a volt lower than the 12v battery, and drop significantly when a load is put on them. If I could run a wire directly from the 12v battery I would. Well, I probably could, but there sure doesn’t seem to be an easy path.
     

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