Harley softail 12 volt system

Discussion in 'General Electronics Chat' started by chizm, Dec 28, 2018.

  1. chizm

    Thread Starter New Member

    Dec 28, 2018
    hello all I'm new here and I have a question and a schematic for you to review, this is for a 1999 Harley softail heritage, using a 12 volt 5 pin standard relay to switch the turn signals to running lamps on demand, make the turn signals act as a running light but when I switched turn signals on with the new relay

    installed kuyukkyn turn signal running light.jpg ,
    for some reason the turn signals won't flash, but the light goes out, so I was hoping someone could look at the schematic and make any recommendations or new schematic that someone has the experienced enough to know what to actually do in this case.
    thanks a lot this is a great forum and
    I wish you a Merry Christmas and Happy New Year
  2. bwilliams60

    Senior Member

    Nov 18, 2012
    Merry Christmas and welcome to AAC.
    I am not sure what it is you are hoping to achieve, but right now I think you are putting the relay coil in series with the flasher relay and the lights. By doing this, there is not enough power to activate the relay. Do you have a schematic for the bike?
    The relay coil should be activated by switched power on 86 and 85 to ground or feed it power on 86 and switch 85 to ground it.
  3. Tonyr1084

    Distinguished Member

    Sep 24, 2015
    First, I know nothing about Harley electrical wiring. BUT here's what I know about blinkers / flashers: For many years the most common method of controlling blinking lights has been to use a bi-metallic strip, a short length of heater wire and a set of contacts. When you turn the blinker on, current passes through the heater wire, on to the bulb. The amount of current being drawn is dependent on the bulb. If the bulb doesn't draw enough current then the heater wire doesn't produce enough heat. I'll get to the "Heat" part of it in a moment. The proper bulb (not relay coil) causes sufficient current to be drawn through the heater wire thus causing the bi-metallic strip to bend and break the electrical circuit, thus turning the blinker off. The bi-metallic strip cools and remakes the contact and the current flows again, thus once again heating the wire. This process goes on until you shut the blinker off.

    The purpose of the heater wire is to heat up the bi-metallic strip. The necessary current is drawn based on the bulb. If you replace the bulb with the blinker module then there is likely insufficient current to cause the afore described process from occurring.

    Modern blinker control modules are electronic, that is - not based on heat produced by current drawn by a bulb. This new module is something I don't know anything about as I've never disassembled one and looked at its wiring. It's possible the relay coil does not present enough voltage drop to actuate the blinker control circuit. In my truck, if one (of two) bulbs goes out then the blinker module will hyper-flash (flash twice as fast as normal; this is an indication to the driver that one of the bulbs is out). My truck and your Harley may have common wiring OR may be completely different. That's why I opened with the fact that I know nothing about Harley wiring. But I suspect your blinker isn't working because the relay is not presenting the proper load for the module to begin the blink process.

    Not the most helpful post, but perhaps if you understand what's going on you may be able to sort out the problem. Good luck.
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
    Turn signal bulbs are the same as the brake lights in brightness so would over power the other running lights. And would also be confusing to many other drivers.
  5. Reloadron

    Distinguished Member

    Jan 15, 2015
    On my 92 Electroglide my front turn signal lamps are 1157 bulbs so dual filament and my rear turn signals are just 1156 single filament. Trying to find your bike but my Clymer manual is only a 84 to 98. I know on some bikes doing what you want to do is not a problem but on others it becomes a nightmare.

    As drawn in your schematic I can understand the effect you are getting and as mentioned, as drawn you have a relay coil in series with your turn signal line. My old 92 actually uses a turn signal module which is fussy about what is out there for lamp bulbs.I am guessing your 99 also has the turn signal module configuration where you have a left and right line out of the module.