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Faulty Head unit or car?

Discussion in 'Gen 3 Prius Audio and Electronics' started by C. Alan, Oct 17, 2011.

  1. C. Alan

    C. Alan Junior Member

    Joined:
    Aug 22, 2011
    10
    1
    0
    Location:
    Tehachapi
    Vehicle:
    2011 Prius
    Model:
    II
    Now, I know there have been numerous issues with the FM recpetion with the factory head units, but I just installed a new Pioneer and I now have a similar problem.

    The HU I installed is Pioneer SPH-DA01 AppRadio, and for the most part it works great. I primarily listen to music stored on my Iphone, and this HU has a pretty nice interface for that.

    The problem is with the radio part of the HU. FM stations come in ok, but I get absolutly no AM stations. I noticed this when I powered it up when I was doing my test fit, and I did check the antenna connection, and it appears to be good.

    Is there anything else I should check that would affect the AM reception? Does the antenna require a power supply for a signal booster perhaps?

    I also need to work out a way to bench test my pioneer head unit to see if the AM tuner works outside the car.
    Thanks,
    C. Alan
     
    #1 C. Alan, Oct 17, 2011
  2. rrg

    rrg Active Member

    Joined:
    May 18, 2010
    458
    120
    41
    Location:
    East coast - NJ
    Vehicle:
    2011 Prius
    Model:
    Two
    I am looking at diffrent things for better FM.
    I am having no luck with low pass filters.

    I have read longer antenna's are supposed to be better?

    Maybe look to try a longer antenna instead of the short stud stock one we have now. I read someone took the ant. off and put a long wire with an eyelet and seemed to help.

    I know ebay has 16" ones I have not pulled the trigger yet.
    I am looking for someone who has one I can try first.

    my2cents.
     
    #2 rrg, Oct 17, 2011
  3. C. Alan

    C. Alan Junior Member

    Joined:
    Aug 22, 2011
    10
    1
    0
    Location:
    Tehachapi
    Vehicle:
    2011 Prius
    Model:
    II
    Bingo, problem solved.

    I did solve my own problem tonight.

    I did some more digging through the forum, and I found that yes, there is an amp built into the am/fm antenna. It is powered off the wire in the harness that typically is used for powered antennas. In the case of the Metra aftermarket Toyota harness adapter, it is the blue wire.

    My Pioneer head unit did not come with a power hookup for a powered antenna, but there is a pre-amp power hookup. In the pioneer installation manual, it states that this connection cannot be used for anything that will draw more than 300ma, and specifically states not to use if for a powered antenna.

    So I got out my 200ma maximum amp meter (it was fuse protected), and used it to connect the pre-amp power output on the HU to the blue power antenna lead in the Metra harness. Sure enough, with the connection made, the radio signal got much stronger, and my amp meter read only 35ma being drawn :rockon:. So, I went ahead and hooked the pre-amp power lead to power antenna lead, and I now have a much stronger FM signal, and a pretty good AM signal as well.

    So for future reference, the 2011 Prius II does have an amplifier built into the am/fm antenna. From my testing, when operating, it draws about 35 milli amps from a 12 volt source.

    --C. Alan
     
    #3 C. Alan, Oct 18, 2011
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