Neutral Light question 787' R100/7

Discussion in 'Airheads' started by therealbatman, Apr 21, 2014.

  1. therealbatman

    therealbatman "Godfather"

    Joined:
    Nov 19, 2006
    Oddometer:
    554
    Location:
    Cadillac, MI
    The neutral light comes on when the clutch lever is pulled in and goes out when the lever is out.

    The neutral light, lights when in neutral.

    Any ideas?
    TYIA
    #1
  2. Peanuts

    Peanuts Long timer

    Joined:
    Sep 12, 2009
    Oddometer:
    1,891
    Location:
    Beautiful but often rainy North Yorkshire, UK
    Something wrong with the diode.

    That's what the diode is there for, it allows the clutch switch or the neutral switch to let the starter relay do its thing, but only the neutral switch brings on the neutral light as just the neutral switch and neutral light are down stream of the diode.
    #2
  3. LonerDave

    LonerDave Been here awhile

    Joined:
    Aug 17, 2011
    Oddometer:
    127
    Location:
    Lisbon, WI
    #3
  4. therealbatman

    therealbatman "Godfather"

    Joined:
    Nov 19, 2006
    Oddometer:
    554
    Location:
    Cadillac, MI
    Thanks LonerDave....

    By chance would you have a photo of what you did?

    Electrical stuff just baffles me, :huh (even though it may be simple to most) and I do not want to fry my wiring harness.

    Thank you.
    #4
  5. LonerDave

    LonerDave Been here awhile

    Joined:
    Aug 17, 2011
    Oddometer:
    127
    Location:
    Lisbon, WI
    I knew I should have taken a pic before I closed it back up! Will try to remember tonight.
    #5
  6. LonerDave

    LonerDave Been here awhile

    Joined:
    Aug 17, 2011
    Oddometer:
    127
    Location:
    Lisbon, WI
    Assuming that your fuse block is similar to mine, find the terminal marked LKK. Located in brown/black section near lower right corner.

    [​IMG]

    If you were to flip the board over, you'd see the diode we want to "replace". Note that it connects terminal LKK to terminal 85b, and that the stripe on the diode is towards LKK.

    [​IMG]

    Here's a crummy pic of the diode and connectors. I used a Radio Shack 3 amp 400 volt diode, but I think you can use 1 amp (Bill Harris says the diode is numbered 1N4001 -a 1A diode). Attach a female spade connector to the end of the diode that DOES NOT have the stripe, and a male connector to the end with the stripe.

    [​IMG]

    I folded the leads coming out if the diode, inserted them into the connectors and crimped. Then, for that hacker touch, wrapped the whole assembly with duct tape (for insulation and some structural strength).

    Then unplugged the brown/black wires going to LKK, slid diode assembly onto male connector at LKK, and attached brown/black wires that used to go to LKK. Hard to see in this pic, but it fits between brown/black wires and terminal on fuse block.

    Hope it helps.

    Dave

    [​IMG]
    #6
  7. therealbatman

    therealbatman "Godfather"

    Joined:
    Nov 19, 2006
    Oddometer:
    554
    Location:
    Cadillac, MI
    Thanks a bunch.:clap...I'll be stopping at Radio Shack this week.
    #7
  8. flemsmith

    flemsmith lurk

    Joined:
    Apr 20, 2006
    Oddometer:
    831
    Location:
    Apache Junction, Az
    Sorry, but I'm a little confused. Couldn't you just unsolder the old diode and solder in a new one?

    roy
    #8
  9. Warin

    Warin Retired

    Joined:
    Aug 30, 2012
    Oddometer:
    3,133
    Yes. You could. Unfortunately removing the board means all the plugin wires have to come off, two bolts .. then remove diode, put new one on, two bolts and wires back on. An add on diode is less work. And it is how it is done on later models.

    Your choice. :1drink
    #9
  10. Big John Sny

    Big John Sny Been here awhile

    Joined:
    Jul 3, 2009
    Oddometer:
    853
    Location:
    Irving, Tx
    Yes, he could, but his solution is a lot simpler than pulling the entire board out. The diode in the board is still making a connection. The diode is just now acting like a check valve that is stuck open. It is letting flow go in both directions. He is just adding in another check valve further down the pipe where it is a bit easier to access.
    #10
  11. Big John Sny

    Big John Sny Been here awhile

    Joined:
    Jul 3, 2009
    Oddometer:
    853
    Location:
    Irving, Tx
    You beat me to it. :D
    #11
  12. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

    Joined:
    Sep 29, 2010
    Oddometer:
    6,636
    Location:
    Big Island of Hawaii
    Yeah, if your test shows a bad diode, I'm leaning towards pulling it all out to do it right and check and clean all the connections in the meanwhile. There's only like, what... 50 wires in there. What could go wrong? :eek1 I think I better disconnect the ground wire... :getiton
    #12
  13. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

    Joined:
    Sep 29, 2010
    Oddometer:
    6,636
    Location:
    Big Island of Hawaii
    Shouldn't that be a 3 amp 40 volt diode?
    #13
  14. Warin

    Warin Retired

    Joined:
    Aug 30, 2012
    Oddometer:
    3,133
    If the diode rating is over

    say 20 volts
    umm .. 3watts 12v = 3/12 = .25 A .. allow surge for cold light say 0.6 Amps

    then things will be fine.
    The 1N4001 are common and cheap. Finding one to exactly match the original speck is a waste of time ... it is not a critical component electrically.
    #14