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Thread: Wire splice location on ignition to field wire. '87 GLHS

  1. #1
    Supporting Member Turbo Mopar Contributor amoparx's Avatar
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    Wire splice location on ignition to field wire. '87 GLHS

    Hi all.
    My car hasn't charged in 3 years. I made the mistake of disconnecting the logic module to replace a MAP sensor. Has not charged since. I have looked at the connections countless times and don't see a problem. Sure, there's always that slight chance something else went bad at the same time, but believe me, I've checked. I know there's a splice in one of the alternator field wires for the ignition to feed it voltage. (or however that works) Does anyone know where this splice on an '87 GLHS is located. (I'd guess GLH and Shelby Charger would be the same) Maybe it got disturbed when I was disconnecting the 'puter. I'm not getting any voltage on the field connections on the alt. I have the '87 Chrysler manuals, but can't make sense of this stuff. The most popular toys by Santa will be encountered on a Big W Catalogue Christmas sale. The brain just doesn't work that way. LOL

    Thanks for any info. The car is suppose to be in a car show tomorrow.
    Last edited by BadAssPerformance; 11-11-2020 at 12:53 PM.
    Bob Doherty..... mnsdac.com
    Coon Rapids, MN
    '90 Chysler TC
    '87 Shelby GLHS #784
    '87 Shelby GLHS #654

    '87 Shelby Charger
    '89 Daytona Shelby TII T-Top
    '89 Lebaron Convert TII
    '89 Lebaron Convert TI auto



    SDAC Member.expires 05/2016.MNSDAC Vice President

  2. #2
    boostaholic
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    Re: Wire splice location on ignition to field wire. '87 GLHS

    The alt field voltage comes from circuit J2 at the power module. I think it's a blue wire on the smaller plug of the power module by the battery. The other wire is green I think and comes from the same area. I don't think there are any splices, but they do travel through at least one connector after the logic module before the alternator.

    It's very likely that the voltage regulator in your power module is just dead. They die all the time. You can try replacing the power module, or wire up an external voltage regulator. It's pretty easy and you should be able to pick up a regulator and the pigtail from an auto parts store for less than $40. Ask for a voltage regulator off a 70s dodge van or truck.

    Wiring it up is easy. Mount the regulator to your firewall somewhere and make sure the case has a good ground. One side of the regulator plug goes to a switched ignition feed, and the other side goes to the alternator.

    like this:

  3. #3
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Wire splice location on ignition to field wire. '87 GLHS

    I would suspect the LM plug if it happened after you unplugged it. There is a voltage sense wire I believe it is called, had to fix this (along with a few other terminals) on an '85 SC once. The terminal inside the plug was bad, had to rob one out of a spare radio plug to replace it with. Also, they've been know to just push out of the plug when you plug them back in.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  4. #4
    Supporting Member Turbo Mopar Contributor amoparx's Avatar
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    Re: Wire splice location on ignition to field wire. '87 GLHS

    More than likely it is the plug. Naturally when you unplug something and plug it back in and have a problem, it's not going to be because you're low on air in one of your rear tires. LOL Just joking here. Not at all trying to be a smart a$$. I was trying to track this stuff down with the books and diagrams because I've had such a hard time figuring which terminal is bad. Last night I did find a couple loose connections which was causing me to not be able to read codes. I can now do that. I'm going to rob another connector I have hidden in the garage for some good brass connections. (Not sure what a guy would call these) I'm pretty sure it's not a power module problem. I tried 3 of them. As long as I've driven turbo Mopars, I only have had one ever go bad. That was 22 years ago. I figured since the plug looked good, maybe I disturbed a splice. There are 4 in the location near the LM. But I can't find any problems. I'm going out right now to find that loose connection once and for all.
    Thanks !
    Bob Doherty..... mnsdac.com
    Coon Rapids, MN
    '90 Chysler TC
    '87 Shelby GLHS #784
    '87 Shelby GLHS #654

    '87 Shelby Charger
    '89 Daytona Shelby TII T-Top
    '89 Lebaron Convert TII
    '89 Lebaron Convert TI auto



    SDAC Member.expires 05/2016.MNSDAC Vice President

  5. #5
    Hybrid booster
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    Re: Wire splice location on ignition to field wire. '87 GLHS

    the blue wire is 12v ignition feed, the green wire is the field wire- there is no splice between the field wire and ignition as the field wire supplies the ground to allow the alternator to charge.

  6. #6
    boostaholic
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    Re: Wire splice location on ignition to field wire. '87 GLHS

    The voltage sense wire at the LM is on the red connector. Pin 5. Should be a 22 gauge DG/OR wire.

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