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Thread: How can I determine what wire powers my amp & sub? Need some help, here!

  1. #1
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    How can I determine what wire powers my amp & sub? Need some help, here!

    I'll be blunt, this is going to be a long-drawn post simply because I've never done this before and I've been working on this for a while now.

    When my truck was originally purchased, the original owner opted to buy the "upgraded" sound system which includes a sub-woofer and a small amp to power said sub under the center console. I've since installed an aftermarket player and am now trying to figure out how to use the amp and sub-woofer already in place.

    My problem is that I'm unable to figure out what wire powers the amp, and which ones drive the sub.

    Aftermarket dual-DIN player.


    This is most likely the connector I need.


    This is the factory amplifier. The four solid-colored wires (white, black, red, blue) are the sub-to-amp wires. The large connector goes up behind the dash.


    These are the wires found on the connector that exits the amp.




    The connector contains the following:
    • Red/Green
    • Red/Green
    • Blue/Black
    • Blue/Black
    • Red/Purple
    • Green/Purple
    • Green/White


    With a test light, I've been trying to find what wire turns on the amp with ignition/key. All I've been able to determine is that both Red/Green wires are constant 12v leads. I'm assuming that the Blue/Black wires are grounds.

    That leaves:
    • Red/Purple
    • Green/Purple
    • Green/White


    Note that these wires also appear on the small connector I referenced to above. I'm assuming that means that two of them are the subwoofer's positive and negative terminals, but I have no idea what to do now to determine which is which.

    Any help would be a blessing. Hell, help me finally figure this out and I'll send a couple of bucks your way.

    Specs:
    Ford Ranger FX4 2009
    Pioneer Premium Sound System
    Last edited by steelfrog; 04-07-2011 at 08:06 AM.

  2. #2
    Maximum Bitrate kegobeer's Avatar
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    Have you tried a Ford Ranger forum? That's probably the best place to find out about the amp and sub you have.

  3. #3
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    Quote Originally Posted by kegobeer View Post
    Have you tried a Ford Ranger forum? That's probably the best place to find out about the amp and sub you have.
    I have. Unfortunately, there seems to be very little existing knowledge about them. The wiring from one year to the next changes constantly so what little information I've found regarding previous models do not apply to my own. I'm basically looking for a way to test the wires at this point and have lost hope of finding a diagram.

  4. #4
    Constant Bitrate dna59's Avatar
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    Metra or scosche doesn't make a harness for it?

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    Well, Metra has a few kits for the truck, specifically part #70-5516, but I think this was actually made to integrate an aftermarket amp into the stock player, rather than the other way around. At least, that's what I've gathered by looking up the part in Google. Scosche makes none.
    Last edited by steelfrog; 04-07-2011 at 10:37 AM.

  6. #6
    MySQL Error soundman98's Avatar
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    first off, please tape those wires so they don't short out.. after a couple of my earlier train-wrecked installs, bare wires scare me..

    anyways, i think i need some pics of the other harnesses..

    i started researching this, and i think that metra-online is screwed up...

    my family has a 96 ranger with what i believe to be a standard audio system. (standard am/fm/tape deck, but front speakers had a 'premium' logo on them). this deck uses 2 metra harnesses-- a grey one and a black one--they look identical to this, but, as you can see, those specifically say they are for bluetooth radios 98, and up... and if i search for parts on metras site for my 96 ranger, these harnesses never come up... this truck has been through 3 teenage drivers-- it always starts with the factory deck, and then me, or one of my brothers bought a new deck once we started driving it-- i have all but memorized the connections to the radio from swapping it out so many times...


    so i blame metra for giving your the wrong part number..

    then i checked crutchfield which is usually pretty consistent with getting the correct amount of info-- they say that there is not any harnesses available..

    at this point, if it were my truck, i would rip out all the stock gear and replace it with budget car audio stuff... it's usually not worth the hassle to figure out the way that the oems wired it for something like this-- as you've found, they like to change wire colors in the middle of vehicle runs which makes it really tough to trouble shoot..

    edit: and after starting to type the way to come to a solution, am realizing that it would be a whole heckuvalot easier to just rip it all out and install some budget car audio gear...


    but, your here posting, so i am sure that you would rather work this out then rip out the old gear..

    there are 2 common types of amps that OEM's use.
    1. accepts low-level inputs: low-level audio is what gets transmitted over RCA cables. if you connect a volt meter to the audio signal cable going to the amp, you should get a reading no more then 5v or so..

    2. accepts high-level inputs: high-level audio is what comes out of the speaker wires of any head unit. i believe these should measure above 5v with a volt meter..

    once you determine which type of amp you have, it helps determine which harness you need-- you would need to either buy a harness with RCA's on it, or figure out which wire goes to which speaker wires.


    if you have high level, this will get increasingly more complex-- as you not only need to figure out which wires go to which speaker-- both inputs, and outputs, but there is always a chance that the sub could have it's own input wires-- further complicating things.

    and the way to power amps on are all over the place as well-- while many amps use a 12v trigger on one of the wires, some amps use a 5v dc signal on one of the audio inputs to turn on...

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    Quote Originally Posted by soundman98 View Post
    if you have high level, this will get increasingly more complex-- as you not only need to figure out which wires go to which speaker-- both inputs, and outputs, but there is always a chance that the sub could have it's own input wires-- further complicating things.
    The speakers are working correctly using a harness kit. There are three harnesses behind the head unit:

    • Large - Currently used by my head unit. The "main" harness if you will.
    • Medium - I believe this one carries the aux input and Sirius.
    • Small - The four-wire shown above in the pictures, which I suspect carries the sub.


    I'll try to take a picture of all three in a few hours.

  8. #8
    Maximum Bitrate kegobeer's Avatar
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    You can always go to your local Ford dealer, give them your VIN, and they will print out the radio wiring diagrams for you.

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    I'VE MADE PROGRESS!

    Okay, here's what I've done:

    1. Reinstall the stock head unit and plug everything back in.
    2. Ensure that the subwoofer operates as expected. Passes with flying colors.
    3. Undo a single connector, restart the car and check whether the subwoofer still operates.
    4. The terminal powering the subwoofer is the suspected 4-wire unit. Other connector is off and sub performs flawlessly. (Hurray!)
    5. Using a voltmeter, check levels of all four wires while plugged in and operating.
    6. Voltmeter is grounded. Using positive terminal to prod.


    Here are my results. THIS IS WHERE I NEED HELP!

    • Red/Purple: Steady 2v line. Turns off the subwoofer when "reading" voltage. I'm not sure if this means that this is the amp power on? If it's only 2v, is it safe for me to plug this in to the ignition 12v line on the other connector?
    • Stripped wire: As expected, it's a ground. No idea why the previous owner stripped it all the way through, though.
    • Green/Purple: Subwoofer "pops" when inserting prong into socket. Reduces the subwoofer's "power" roughly by half when reading. Quite an audible difference. Not sure if this means it's positive or negative.
    • Green/White: No reading. No activity. Assuming it's position or negative subwoofer terminal.
    Last edited by steelfrog; 04-07-2011 at 07:27 PM.

  10. #10
    MySQL Error soundman98's Avatar
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    i believe that the green/purple, and green/white pairs should be the sub signal-- usually the negative part is grounded to the chassis-- if you remove both these wires, teh sub should stop working all together. you might need to use the meter on the AC setting to read any fluctuation here-- try a real bassey song for this test..

    red/purple--probably not safe to plug into the standard 12v power.. does this line turn off with the radio? if it does, that is the line you need.. though i kinda think that the ground is used as a referance-- so be prepared to require both for the amp to work. i have a link on my laptop to a switching power supply(a site that oldspark recommended-- maybe he's got the link closer at hand) that you should be able to use to get a 2v output with minimal heat.

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