FXDF brakelight problem

Discussion in 'Dyna Models' started by LINZ, Aug 11, 2011.

  1. LINZ

    LINZ New Member

    I have an '09 FatBob. This year was the first year it got ridden in the rain or on wet roads. The tail light filled with water until it hit the hot bulb and broke it. I drained the lens, dried everything out and cleaned all the contacts. New bulb and everything was working fine.

    I was on a road trip and the same thing happened twice more in rainy weather. I just drained it out and replaced the bulb and everything worked fine until the next rain. It rained again on the last strech to home so when I got home I drained, dried and cleaned everything again. This time the taillight would work but no brakelight. I also now noticed the lens had a fine crack in it. Whether this was the original problem or it happened from dropping the lens on one of the bulb changes I don't know. I didn't mess with it anymore as I decided to order the LED tribar light.

    Anyway, I just replaced the stock light with the new one. The only thing reused was the pin housing/circuit board that mounts in the tail light base. All the contacts were well cleaned before reinstalling.

    Again, everything works except for the brakelight, whether applying front or rear brakes. Is there anyone smarter than I that can shed some light on where the problem may be?

  2. Hoople

    Hoople Account Removed

    Go to the hydraulic stop light switch mounted at the rear master cylinder. There should be two wires attached to the switch. Red/Yellow & Orange/White. The orange/white should have 12volts power to it when the ignition is ON. If it DOES, then while stepping on the rear brake, do you read 12 volts on the Red/ Yellow.?

    That switch transfers battery power from the orange/white to the Red/yellow in order to light the bulb. You should also see 12volts on the Red/Yellow wire when you apply the FRONT brake also.

    See if that is happening.
  3. LINZ

    LINZ New Member

    It seems there was power to both terminals. I disconnected the harness going to the tail light. Now there is power to only one, and to the other as well when the brake is applied. I guess the brake light was always on and not shutting off.

    Looks like the 2 wires are shorting somewhere. I would think the only possible place would be in the circuit board mounted in the tail light housing. I will take it apart and use the ohm meter to check it out.

    Thanks alot.
  4. glider

    glider Veteran Member

    Check the bulb to be sure it's an 1157 and that it's installed properly.
  5. LINZ

    LINZ New Member

    No bulb. New led tail light. Old one was correct. There seems to be quite a bit of water, dirt etc that comes from under the fender into the tail light base where the circuit board is mounted (where everything plugs into.) I cleaned it real good when installing the new base and tail light but I'll check that next. I really can't see anywhere else power could feed between the 2 circuits.

    It was the circuit board. As I said I had cleaned the pins real good. It must have corroded inside, my meter showed a couple circuits were shorted together. Nothing $35 at the dealer couldn't fix. I would have just cut the plugs off, made my own connectors and done away with the board altogether but I was short on time and replacing it was the quickest.

    Seems like a bad design. Alot of grime and moisture gets thrown up in there. I'll add checking/cleaning it to my routine maintainance but if it happens again I will remove it permenantly.

    Also, I think the LED light looks great along with the smoke lenses on the turn signals. -Thanks for the replies.

    Last edited by a moderator: Aug 13, 2011
  6. ogri

    ogri Member

    just happened to mine . what a (EDIT) design .
    now waiting for a circuit board .
    then i will fill it up with sillicone .
    dealer recons he's never heard of this before = (EDIT)
    loads about same problem on interweb

    circuit board fried , full up with water

    Please read this...
    HDTalking Language Policy - Harley Davidson Community
    Last edited by a moderator: Apr 11, 2012
  7. R_W_B

    R_W_B Senior Member

    The Fat Bob has a kinda duckbill rear fender. I'm not familar with the details of the cable entry since mine is a Street Bob. But you might try doing what I did on mine when I had it apart last.

    First off put dielectric grease around all the plug in connections to help keep corrosion out.

    Second off go to Ace Hardware and buy a few inches of their self adhesive "Stair Tread strips" (they are about 4" wide). This stuff is handy for all kinds of things. Also buy a small squeeze tube of clear silicone adhesive. Cut a rectangle out of it just a bit larger than the entry hole for the lighting wiring. Then cut a slit up from the bottom to the center of this rectangle. Remove the adhesive paper blocking, move it around the wiring and stick it to the entry area overlap.

    Plug up any slight openings left with clear silicone. Also put some slicone around the edges of the strip to help hold it on.
    with the tail light lens off

    Then check the gasket on the lens before you put it back on.

    I did all of this on mine and I have ridden for long periods in hard rain and never had a problem.