FLHTCUI - Voltage Spike w/ Passing Lamps

Discussion in 'Touring Models' started by Arpey, May 23, 2009.

  1. Arpey

    Arpey New Member

    '99 FLHTCUI - Transient Voltage Spike (16V) while turning on Passing Lamps yesterday. Voltage came back to normal (~13-14V @ 3K rpm @ 70 mph in 5th gear) after shutting off passing lamps. Later turned Passing Lamps back on and voltage dropped to ~12V, and then returned to normal after turning lamps off.
    Also, fuse blows when hard expressway exit ramp braking with passing lamps on, with voltage drop, taking out all the lamps. This doesn't happen when lamps are off as voltage remains constant.
    Have traced wires, no apparent cracks or breaks. Passing lamps are well grounded. Have a multimeter and can trace but do not know where to start.
    Any suggestions what the problem may be?
    Thanks, RHP
  2. glider

    glider Veteran Member

    Check in the lamps themselves where the wire enters through the bottom. May want check for a grounded wire in there.
  3. Arpey

    Arpey New Member

    The wires in the lamp housing are good. The ground wire is well attached to the housing.
  4. dangerdan

    dangerdan Junior Member

    I would pull the fuse and hook up an ohm meter on the NON voltage side of that fuse and not the 12v side. and connect the other to a good ground. If you have a meter that buzzes thats even better.

    Start twisting/bending wires at pinch points or any entry points into the lamp housing.. Operate any switches or try removing lights from the socket.

    Do this with the bulbs in then out.

    This question is for someone with more experience , but is it possible the voltage regulator cant handle the extra load and is trying to overcompensate.