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Subject: Headlights Ground Wire

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Robert Angney    Posted 03-23-2020 at 09:16:08 [URL] [DELETE]        [Reply] [Email]  
  • Headlights Ground Wire
  • Our 1940 9N has CM HALL style headlights. We just got the tractor wired up properly and we're working on the headlights. Can you show us a pic of where the ground wire is connected on the headlights? We've tested the lights and they work when we run a jumper from the base of the bulb to the frame of the tractor. Just to know where/how to connect a permanent ground wire.

    acadianbob    Posted 03-29-2020 at 12:50:34 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • I must have too much paint on my doglegs? My headlights will only work if I run a separate ground wire. Nice bright light then . . .

    The wiring harnesses are all new so there is no connection problem with the hot wire.

    Tim Daley(MI)    Posted 03-24-2020 at 06:38:28 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • Our esteemed Webmaster Tyler Neff has this archived CM HALL HEADLIGHT info SEE LINK
    . Part of the beauty of the OEM 6V/POS GRN system used by Ford was that lights only required one wire to power as the ground was applied to any metal surface. You can accomplish the same thing with 12V as well by the way. Running a separate wire to the lights is not needed when done the correct way.

    Tim Daley(MI)

    Robert Angney    Posted 03-24-2020 at 10:09:48 [URL] [DELETE]        [Reply] [Email]  
  • Re: Headlights Ground Wire
  • OK. What is the correct way to do this so that I only have to use one wire?

    Tim Daley(MI)    Posted 03-24-2020 at 14:38:59 [URL] [DELETE]        [Reply] [Email]  
  • Re: Headlights Ground Wire
  • Bob-
    I thought that was what you were asking in your initial post. The 6V/POS GRN system using one wire, the HOT (-) wire to the lamps. The GRN (+) wire is connected to each lamp internally to the shell metal ground. You just need to ensure all rust, paint, and crud is removed to make a solid connection. I don't have my Halls easily accessible so can't get out mine and take photos. N-Series Headlights were never installed at the Rouge or later, the Highland Park) plants. Lighting kits were only offered as dealer supplied optional accessories. You got two headlights and one tail light with all the needed hardware and wiring. There was a wiring diagram included. I have one -see picture but if you want a hard copy, email me and I will send one to you. The sketch is 17 x 22 or so too large print here.


    FORD 8N LIGHTING KIT SKETCH:

    Tim Daley(MI)

    Dean    Posted 03-24-2020 at 12:16:28 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • The first step is to assure that there is a proper electrical path from the ground (OEM +) terminal of the battery to the headlamp housing.

    The return (ground) path is through the headlamp housing, mounting stud, hood, etc.

    A one wire system will NOT work properly without good electrical connections between battery and lamp bulb.

    Assuring such good connections can be challenging on decades old machinery, and is one reason why I run separate ground wires.

    Dean

    Robert Angney    Posted 03-24-2020 at 13:08:26 [URL] [DELETE]        [Reply] [Email]  
  • Re: Headlights Ground Wire
  • If I run a wire from the light to the battery, would I be able to run a wire to the battery from the light switch in order to turn on the lights?

    Tim Daley(MI)    Posted 03-24-2020 at 15:08:42 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • No, you never wire the lights directly thru the battery. Here is an 8N wiring sketch but the principle is the same for all Ford 6V/POS GRN lighting kits. Wiring is fed thru the light switch. Just8Ns sells a repop ‘like original’ light switch for the early 9N lights –see link. Just8Ns also sells a new lamp bulb for the CM HALL lights.

    FORD 9N/2N WIRING SCHEMATIC FROM THE SERVICE MANUAL:

    FORD 8N LIGHTING SKETCH:


    Tim Daley(MI)


    Dean    Posted 03-23-2020 at 09:30:31 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • OEM ground wire was riveted to headlamp housing.

    Works only if current path through mounting stud and multiple levels of paint and/or rust is adequate.

    I always install internal star washers between sheet metal, reinforcement plate, etc.

    I also run individual ground wire to rear lamp as ground connection through fender/axle trumpet is exceptionally unreliable.

    Dean

    Robert Angney    Posted 03-23-2020 at 12:58:10 [URL] [DELETE]        [Reply] [Email]  
  • Re: Headlights Ground Wire
  • Thank you. Here is what we tried. Since the rear work light works, we took it apart to see where the ground wire was and there was no ground wire, just a wire that went to the switch. We then tested the front lights by grounding them to the headlamp housing and that didn't work. Is the ground wire separate from the the wire that goes to the switch? Is there a specific place to connect the ground wire?

    Dean    Posted 03-23-2020 at 14:04:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Headlights Ground Wire
  • There was no ground wire as built. Rather the lamp grounded through the hood.

    One terminal of the bulb connects to a short wire riveted to the headlamp housing.

    As previously stated, this only works if the headlamp housing is electrically connected to the ground (originally +) side of the battery.

    Dean

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