Close



Results 1 to 12 of 12
  1. #1

    Default Coil wiring on 85 GT

    Just starting to get into my (new to me) 85 GT. Previous owner had an old alarm system hooked up to the coil. I've removed the wires from the alarm system (and the resistance wire to the coil by mistake) and can't figure where the red with light green wire goes when it comes out of the coil. The alarm circuit had it spliced going two places. I've read a ton of threads and have printed out the wiring diagram, but I'm confused with the red wire going over to the pass side inner fender by the starter solenoid.

    Full disclosure ... I'm an idiot and those shiny new connectors are my work and after removing the alarm I hooked up everything and started the car just fine. But the car would not shut off with turning off the key and the car would not shut off with removing battery cables.

    So any help I can get, I thank the board in advance. Just ordered service manual too- thanks!

    Name:  IMG_8842.jpg
Views: 120
Size:  113.5 KB

    Name:  IMG_8843.jpg
Views: 121
Size:  101.1 KB

  2. #2

    Default

    Must be a really stupid question...

  3. #3

    Default

    Going from memory now so don't hold me to the details

    I was just looking at this circuit recently on my 1980. I believe the red/grn coil wire goes to the large square connector with many wires right below the coil. Same connector that has the oil pressure/ temp sender going to it. From there it goes back to the ignition switch and somewhere in series with this there is supposed to be a 1ohm ballast resistor (according to the schematics) which is to help limit the current on the ignition module from what I understand. The OEM coils sometimes state they are to be used with an external resistor right on them etc.

    However I was never able to find this ballast resistor on my 1980 and found that this coil wire was running at 12 volts all the time. If the resistor is in place it should drop some voltage at the red/grn wire on the coil connector when the car is running and show 12 volts when just ignition on etc.

    Hope that helps.

  4. #4

    Default

    Quote Originally Posted by at_the_junkyard View Post
    Going from memory now so don't hold me to the details

    I was just looking at this circuit recently on my 1980. I believe the red/grn coil wire goes to the large square connector with many wires right below the coil. Same connector that has the oil pressure/ temp sender going to it. From there it goes back to the ignition switch and somewhere in series with this there is supposed to be a 1ohm ballast resistor (according to the schematics) which is to help limit the current on the ignition module from what I understand. The OEM coils sometimes state they are to be used with an external resistor right on them etc.

    However I was never able to find this ballast resistor on my 1980 and found that this coil wire was running at 12 volts all the time. If the resistor is in place it should drop some voltage at the red/grn wire on the coil connector when the car is running and show 12 volts when just ignition on etc.

    Hope that helps.
    Thanks for sharing- yes this does help. Gives me enough confidence to try it this way and see what happens. Thanks!

  5. #5

    Default

    Just re-read the post again. I assume your main issue is the car not shutting off

    It seems to me that you must have a 12V source back feeding the coil wire/ignition system from an alternator powered source if the car wont shut off when key off or even battery disconnected.

    I believe the alternator hooks in essentially to the battery positive cable and a bunch of fusible links by the starter solenoid...so you may have a wire there hooked in.

    It can be painful...I have poured over those drawings more than a few time trying to make sense of it and match up the wire colors. They are not always easy to read.

    Cheers

  6. #6

    Default

    Also just noticed your coil is mounted on the engine whereas my 80 is mounted on the driver shock tower etc. Square connector I was talking about should be there on driver side assuming 85 is the same as an 80 ?

  7. #7

    Default

    I believe the early 85's were a round coil mounted under breather to manifold by passenger side of carburetor. That's how mine was anyway.

    Good Luck
    Brant

  8. #8

    Default

    OK I went and looked on my 85, the red with light green comes from the coil and goes down to drivers side of the motor where it plugs along with 2 or 3 other plugs into harness part that goes to firewall, hope that helps.

    Brant

  9. #9

    Default

    The wire comes out of the firewall on drivers side into a fuse link located behind the left strut tower. Then there is a splice that splits one goes to the voltage regulator. And the other to the coil. I traced this circuit last year on my 84 because the wire to the regulator was open causing no charge.
    Last edited by Lowetlx; 04-25-2018 at 04:13 PM.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  10. #10

    Default

    Just guessing but could it be the mystery red wire is back feeding your coil and ignition ?

    Curious how did you get the car to shut off....disconnect the red wire ?

  11. #11

    Default

    Thanks for all the replies- yes, I think the red wire connecting through the pass side must be back feeding the power circuit. When it wouldn’t shut off, I panicked a little and killed it by putting it in gear and letting out the clutch while holding the brake. I’ve been afraid to try it again! Lol!

  12. #12
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,961

    Default

    I guess your all on the right track.

    Stock 4-BBL HO's had the coil right there.



Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •