70-5521 Wiring Harness - what's the extra blue wire?

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70-5521 Wiring Harness - what's the extra blue wire?

  • I am installing a new Pioneer FH-P8000BT in my '07 Mustang w/Shaker 500.  I'm including the 5V regulator fix, using instructions located at <link changed to here> <Mod Edit: Removed link due to discussion of video bypass connection. No conveying illegal or unethical information. Please refer to our Code of Conduct. Thanks.> .  I started putting together the harness connections and, oddly, the 70-5521 harness includes a blue wire that is nowhere to be found on the wiring diagram (see here http://akamaipix.crutchfield.com/Manuals/120/120705521.PDF).  The phantom blue wire inserts into the harness next to the orange/white dimmer wire. 

    I think this is a relatively new addition to the harness.  Not only is it absent from the wiring diagram (revision date Jan 2005) but Crutchfield's own picture of the harness does not show the blue wire.   (C'mon Crutchfield!)   I called the support line and the response was that the blue wire ties into the two blue/white amp turn-on leads in the small harness.  For some reason I'd like confirmation from someone who has hooked up this harness.  It doesn't seem logical to tie in the blue wire here.  The amp power flows from the large Metra connector (coming from the vehicle 12V), then through the Pioneer harness (blue/white) to the small Metra harness (blue/white) to turn on the sub amps.  (In my case I have a 5V regulator in between to prevent popping).  Tieing the other blue wire into this group does what?  

    Any and all assistance is appreciated before I blow something up :)



    [edited by: TigerHeli at 11:58 AM (GMT -5) on Sat, Apr 05 2008] Was http://www.mustangforums.com/m_3581800/mpage_1/key_/tm.htm#3581800
  • Interesting - I couldn't find any plug info on the 07 Stang - but - you said the blue wire is right next to the orange/white dimmer wire on the Metra harness.  Is there a wire in the mating position on the factory harness and do you know where it goes?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • Power antenna?

    1995 Chevrolet C1500 Silverado

    Kenwood eXcelon | Diamond Audio | Kicker | RAAMaudio

  • I was able to locate a Mustang wiring diagram that showed the mate to the Metra harness. Based on pin positions the blue wire does not connect to anything on the 05-08 Mustangs.  Since the harness is for multiple Ford vehicles, I assume the blue wire is used in some applications.  My guess would be power antenna too. 

    An additional confirmation is that the Mustang radio harness does not contain a dimmer wire.  The pin position is empty.   Therefore, simply hooking up the orange/white wire between the Metra harness and Pioneer harness will NOT enable day/night mode.  As suggested on most Mustang forums, the orange/white ILL wire in the Pioneer harness requires a separate tap wire to a headlight switched circuit.  Most people are tapping directly into the headlight switch.  This is pictured on the link from my earlier post.

    I will update any changes when I complete my installation.