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Reverse lights only come on (constantly) when lights are on.

Discussion in '1994-2004 V6 Mustang Tech' started by sschmok, Jan 15, 2017.

  1. sschmok

    sschmok New Member

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    I've got a 2002 Mustang V6 and started having problems with the reverse lights a few days ago. When I turn the parking lights on (switch half way out) the reverse lights come on (even when not in reverse). However, the reverse lights do not come on when I have the lights off and actually put it in reverse. I checked for crossed wires, etc. and nothing.

    A little background. I recently installed some halo projector headlights and wired the LED halos into the parking lights in the front. They were working fine and then I noticed they stopped working. I took the lights out and noticed a short between two of the wires, which blew a fuse. I replaced the fuse, fixed the wires, and they work fine now. But I think the issue may have triggered something that is causing my problem. Looking at some of the wiring diagrams it seems like the GEM module has something to do with the reverse light circuit and I wondered if I fried the GEM? Any ideas?
     
  2. sschmok

    sschmok New Member

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    OK, an update. Found out that fuse 11 was blown that powered the reverse switch circuitry. So, the reverse light comes on when in reverse (no lights on). But, the reverse light still also comes on when I turn the driving lights on. Still pointing toward the GEM because the reverse light wiring diagram shows it's connected to the reverse light wires (pin 20). OR I have a wire crossed somewhere but I haven't messed with any of the wires. Any ideas?
     
  3. fasterthanyou

    fasterthanyou Active Member

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    Chasing wiring issues can be tricky but it does sound like the gem module got zapped when messing with the halos
     
  4. sschmok

    sschmok New Member

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    Yeah you're probably right. Does anyone know where I can get a pinout of the GEM? I checked the shop manual but couldn't find anything.
    Thanks.
     
  5. mrwitty_1

    mrwitty_1 Member

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    Hopefully this will help.

    [​IMG]
     
  6. Phil II

    Phil II Cone Destroyer Staff Member

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    How is an exploded view of an automatic transmission pertinent to a need for a circuit diagram?
     
  7. fasterthanyou

    fasterthanyou Active Member

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    Huh?
     
  8. Phil II

    Phil II Cone Destroyer Staff Member

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    See post #5
     
  9. fasterthanyou

    fasterthanyou Active Member

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    I see a pic of a gem module wiring diagram. Where's an automatic transmission exploded view?
     
  10. Phil II

    Phil II Cone Destroyer Staff Member

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    I could be wrong...
     

    Attached Files:

  11. mrwitty_1

    mrwitty_1 Member

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    Well I posted a wiring diagram of a gem module, don't know where your post came from. But it's no problem I won't try to be helpful anymore !
     
  12. Phil II

    Phil II Cone Destroyer Staff Member

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    I captured the image from the mobile application. Your post showed the above picture to me, on my mobile device. I questioned it. I can see from my desktop that I was wrong.

    Thank you for sharing the wiring diagram.
     
  13. fasterthanyou

    fasterthanyou Active Member

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