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Electrical Gremlins

Discussion in 'Norton Commando Motorcycles (Classic)' started by Lineslinger, Jun 16, 2018.

  1. Lineslinger

    Lineslinger VIP MEMBER

    Joined:
    Feb 26, 2017
    Restoring a 74’ 850 Commando Roadster.
    I have all the electrical systems completed. New LED lighting, new wiring harness, new 3 position ignition switch. Replaced all bullet connectors with weatherproof connectors. Wiring completed with all components functioning as they should.

    At this point I decided to run an independent circuit directly from the keyed switch to the new ignition module dedicated to work in conjunction with the Tri Spark upgrade, it’s the ignition upgrade package offered (that I purchased) from cNw.

    I located the desired post on the keyed switch but before running the new lead decided to double check everything once more as a connection pulled loose and I failed to photograph it prior to installing the keyed switch.

    Everything works as before except for the brake light. It has now decided to offer up a lesson in frustration. The running light comes on when key is switched on but no brake light from hand or foot switch, which was working exactly as it should before I pulled the key switch out of the bracket.


    Could someone please post a photo of the placement for keyed switch connections?
    I have dual white wires to single connection , a dual brown/blue to single connection , a dual brown/green to single connection , and a single blue/yellow to single connection.

    Any and all insight appreciated.
    This is a real frustration as I am so close to a restart after 41 years. But, better to be patient and analytical than hurry up and screw up.

    Sorry for the lengthy post, just trying to be clear.
     
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  2. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    I'm not sure about this, but I believe the taillamp ground runs through the frame, and is thus less than reliable.
    Before getting too tangled up, you might run a temporary jumper from battery ground to the body of the lamp, see if it makes a difference?
    And of course, check the bulb (or board, if it's an LED type) to be sure it works at all...
     
  3. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    Yes , trace backwards from the ( tail light) problem using a probe type test light.
     
  4. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Which colour wire "connection pulled loose"?


    As you have a "new 3 position ignition switch" instead of the Lucas 4 position switch then the terminals may be arranged in a different order to the original.
    [​IMG]


    The only ignition switch wire that would prevent the tail lamp working if it bacame disconnected would be white (terminal 2) however, it would also result in other electrical items also not working such as the horn, direction indicators, charge warning lamp (and normally the ignition system but you have rewired it separately).

    Both brake and tail lamp filaments use the same (red) return wire from the (rubber mounted) bulb holder (L917 tail lamp).
     
    Last edited: Jun 17, 2018
  5. dave M

    dave M

    Joined:
    Oct 19, 2005
    Aren’t LED bulbs normally polarity sensitive and consequently don’t work with the normal Norton positive earth system?
     
  6. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Positive earth LED bulbs are available but perhaps we need more information.

    http://www.norbsa02.freeuk.com/goffyleds.htm
     
  7. Lineslinger

    Lineslinger VIP MEMBER

    Joined:
    Feb 26, 2017
    LED bulbs are positive ground, from Mr. Goff whom I found on this forum.
    I had just begun to trace backwards but thought it a good idea to ask on this forum before doing so.
    All other white wire dependent systems function as they should so ground is suspect, I hope.

    Thank you for the insight guys, I will let you know what I come up with.
     
  8. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    My MK 111 came with positive ground Tail light L.E.D. illumination.
    Works great and brighter !
     
  9. XTINCT

    XTINCT VIP MEMBER

    Joined:
    Jan 10, 2012
    It has been my experience in 50 plus years of messing around with vehicles, trailers, and machinery that with any electrical gremlin issue the first place to look is the ground, especially an intermittent failure. After the bulb of course.
     
  10. Lineslinger

    Lineslinger VIP MEMBER

    Joined:
    Feb 26, 2017
    As I stated in an earlier post, here is what I found.


    I had to leave town for a fishing trip and spent the week considering the Gremlin problem from various angles. Once home I was back in the garage the next morning checking a couple of other variables I thought might be responsible for the intermittent brake light. These variables I had in mind did not pan out.
    Still no brake light.
    I disassembled the tail light and began checking connections inside the housing...all good. Light board was good.
    My next step was to confirm the continuity of each wire running from start point to the rear tail light, they all showed continuity....until out of the corner of my my eye I caught a glimpse of the meter doing a quick blink from "zero" back to continuity while checking the hot lead. I jiggled the connector with the meter probe inside of it and found I could initiate the "blinking" or continuity loss by moving the connector a certain direction or by pushing the incoming lead into the connector at a certain angle.

    Gotch'a.

    When installing the new wiring harness I dumped all the bullet connectors and replaced them with sealed weatherproof connectors. Inside the connector a male connection pin had broken but was still making an intermittent connection.

    Sound familiar? An intermittent electrical problem/connection? It was gratifying to nail down the problem...finally. I replaced the bad connector with a new one i tested before installing it.
    The brake light is back to operating as it should.
    I did not use cheap connectors, they are of good quality, but............

    I now have, in the back of my mind, this gnawing concern about the other 10 plus replacement connectors I installed.

    But it was just this one time anomaly right? Right?
     
  11. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    Right!
    Carry on with confidence. Since you now know what to expect and how to deal with it.
     
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