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Thread: Alternator/Batt issue

  1. #1
    Join Date
    Jul 2009
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    Marietta GA
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    Alternator/Batt issue

    ALright. So after 4 long weekends and a 16 hour day yesterday, we finally fired up the Cobra Eaton charged Marauder. The conversion went well but certainly doesn't bolt right on. Everything is done now except for the Intercooler pump wiring, which I'll hopefully get to today.

    So here's the problem. After starting the car up I got a BATT light, and was only getting a reading of 12 volts on the volt meter in the center console. I used the Cobra Alternator (which required notching the frame) and relocated the battery to the trunk. In using the Cobra Alternator, I discovered that the Marauder uses 3 wires plus a large power wire and the Cobra only uses 2 wires along with the power wire. So what I did was use the Large yellow wire and the small green wire from the Marauder harness and connected them to the same color/size wires on the Cobra harness. That left 1 small yellow wire from the Marauder harness that is not connected to anything. My concern is that on the Marauder harness I used 1 outer wire and the middle wire, and on the Cobra harness both wires were on the outer ends of the harness.

    Do I need to use the small yellow wire instead of the small green wire, or is there something else I should look for????

    Any help would be appreciated.

    Thanks, Will..

  2. #2
    Join Date
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    Can't use the Cobra alternator, the controls for the regulator are different. Either switch to a Marauder regulator or get a Marauder alternator and swap the pulley.
    Thanks to Darrin @ BC Automotive:
    $1800 and it was worse than when he started!

    Brian (FordNut) FPG # 1458 of 7838
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    03 MM 300B Silver (Mostly stock, originally wife's car, 370k mi) FPG # 7053 of 7838 or 49 of 417 SB
    03 MM 300B Silver, Stock, wife's next one, 136k mi FPG # 7134 of 7838 or 89 of 417 SB
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  3. #3
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    Jul 2009
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    Can't use the Marauder Alternator. It's a completely different shape and size and doesn't work with the Cobra brackets. Have to use the Cobra one.

    What's the difference with the controls for the regulator.

  4. #4
    Join Date
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    The Cobra alternator is self-regulating where as the Marauder is PCM controlled.

    I've successfully run the Cobra alternator on my set up by replacing the Cobra regulator with a PCM controlled type.
    The regulator from the Marauder alternator will not fit the Cobra if you're trying to swap the two.

    I'll have to go find my notes as to which regulator it was.
    2003 Black 300A (SOLD!!!)
    4.6L with Whipple 3.4
    626rwhp 569rwtq
    My Garage

  5. #5
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    Jul 2009
    Location
    Marietta GA
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    So I played around ewith the wires today. Didn't actually do anything with them, just pulled them apart from eachother to make sure they weren't shorting across one another and I fired her up again and was reading 14 volts with no BATT light. What's the deal. Will it work or won't it. If the Cobra one is internally regulated then can't I just leave the PCM control wire from the Maruader disconnected and let the Cobra alternator do its thing?? Why is it necessary to switch out the regulators??

  6. #6
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    You can run the Cobra alternator with its regulator if you want but I don't think the BATT light will work properly and that would be the only issue. That light is control by the PCM where as the Cobra is controlled by the alternator.
    When I first got mine running, I was getting 13.8+V to charge the battery. The only problem was the BATT light would stay on indicating the alternator off line or low voltage even though that wasn't the case.

    If you're getting 14 V at the battery and no BATT light then you're in the clear. (Though, I'm not sure how.)
    2003 Black 300A (SOLD!!!)
    4.6L with Whipple 3.4
    626rwhp 569rwtq
    My Garage

  7. #7
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    Marietta GA
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    Anybody able to tell me what the 3 wires are for on the Maruader Harness?? 2 yellows with stripes (one thicker than the other) and one green with a stripe. If someone could tell me from a wiring diagram what each is for that would be very helpful.

    I'll post this on SVTPerformance also, but if anyone on here has the ability to look up what the 2 wires on the 03/04 Cobra's Alternator are for, that would be helpful also. 1 yellow with a stripe, and 1 green with a stripe.

    Thanks.

  8. #8
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    I thought you got the alternator working putting out 14V with no BATT light or did I read that wrong?

  9. #9
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    Jul 2009
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    Marietta GA
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    I was only able to run the car for a few minutes after discovering that I had a leak that seemed to be coming from between the lower intake and the Heads. I had to pull the supercharger/lower intake assembly back off and am now having to shorten the 90 degree fitting on the bottom of the intake as well as maybe address the hard line from the water pump for additional clearance.

    I just want to make sure that running the alternator the way I have it set up currently isn't going to fry it, by having voltage going to a wire on the Cobra Alt that it shouldn't be going to. Just wanting to double check the connections before I run it again. The way it's is set up so that it fits in the Marauder, makes it such that it's a royal PITA to remove it if I cook it.

  10. #10
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    You'll find the diagrams you're looking for in this thread.

    http://www.mercurymarauder.net/forum...ad.php?t=47041
    2003 Black 300A (SOLD!!!)
    4.6L with Whipple 3.4
    626rwhp 569rwtq
    My Garage

  11. #11
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    Jul 2009
    Location
    Marietta GA
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    Thankyou. That is incredibly helpful. Don't know why it didn't come up when I searched, but oh well. Odd that they decided with the same year vehicle 03 MM and 03 Cobra to run 2 different theories of wiring for turning on the BATT light. Like I stated earlier, it seemed to be working last time I had it running, but hopefully I'll get a chance to put her back together this week to make sure that it's doing what it's supposed to.

    Thanks again,

    Will

  12. #12
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    I thought the stock Cobra regulator would worked too when I first got my running.
    It took about 2 minutes for the BATT light to come on for me then I realized it wasn't going to work especially after analyzing the diagram.
    2003 Black 300A (SOLD!!!)
    4.6L with Whipple 3.4
    626rwhp 569rwtq
    My Garage

  13. #13
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    It looks as though what was stated in the post that you linked a couple of replies back, about disconnecting pins 45, 7, and 70 from the PCM, and connecting 45 to 70 or 7 to 70, depending on which one is feeding half battery voltage back to the system, should do the trick though. Without replacing the regulator.

    I'll have to get the voltmeter on the various pins and see what I come up with. Regardless of the BATT light though, the Alternator should function (charge the battery) as long as the main BK/OG is hooked up and the YE/WH is hot and feeding the alternator harness, right??

  14. #14
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    I suppose it would work, but you'll lose the ability for the PCM to control the alternator.
    In the tune, there are scaler and tables for the PCM to control the alternator such as voltage at idle, voltage-temperature compensation, WOT alternator cut-off min-max times, voltage to determine charging system good or low.

    I guess it's really no big deal not to have those functions.

  15. #15
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    Doesn't look as though the Cobra Alternator was ever set up to be controlled in this manner anyway right?? I don't know why they did it so differenlty on 2 cars that were from the same manufacturer and the same model year. Makes no sense.

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