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JoeP's XR1200 Section

How to convert single function LED turn signals
into dual function LED indicators.

SMT WTFS


If you have updated your Sportster (XL or XR) with LED turn signals, chances are you lost the ability to have running lights when you did that upgrade. Also, you likely had to add Load Resistors to each LED's electrical circuit so that the Harley-Davidson ECM does not detect an electrical problem on with the motorcycle.

This procedure will show you how to get your LED turn signals to have running light functionality for about $10 in electronics.

List of things you will need:
That is the under $10 list.

If you want to make the install look snappy, here is a list of optional things that will run the price up but make your installation look nice and professional:
  • Heat Shrink
  • 18 AWG Wire
    A total of 2 meters, or 6 feet, of wire should be plenty. The link above is just to some plain BLACK wire, but various colors of wiring should be purchased if you really wanted to be anal and do it right (like me).
    • Black - Ground
    • Blue - Running Lights Power
    • Brown - Turn Signal Power, Right Side
    • Violet - Turn Signal Power, Left Side
  • Cable Ties (UV rated)
  • Spiral Cable Wrap
By following the traces in the wiring diagram below, you will notice the Front Turn Signals are wired to the Rears Turn Signals and the Dash Indicators. Once you add power from the Running Lights (BLUE wire) to the Front Turn Signals, the Rear Turn Signals are automatically wired up, but so will the Dash Indicators. My use of diodes (further below) solved this problem.

Wiring Diagram
(Click to SuperSize)


When adding power from the Running Lights (BLUE wire), two (2) 470 ohm resistors need to be included in series or the LED Turn Signals will always be on full brightness.

470 Ohm Resistors

Here is how the underside of my gas tank looked when I was completed.

Actual Turn Signal Connector
(Click to SuperSize)


Left like this, the Load Resistors are always going to have current flowing through them, so they will always be hot. Also, you are not going to notice anything from the Running Lights power because all of the current is going to flow through the Dash Indicators (path of least resistance).

If done right, your wiring should look nice and clean under the gas tank where the Turn Signals Connector is. I even added a note for myself so I'd be able to quickly tell which wires went to what side.


(Click to SuperSize)
When the TSM activates the right blinker (wire 6), current will flow to the LEDs on the Right Front and Right Rear as well as through the Red Load Resistor and to ground. It can not flow into the left blinker's path (wire 5) because the diode there only allows current to flow in one direction. What this also does is allows you to wire up your LEDs using only one load resistor. The left side and the right side can both use the same one.

Below is what it looks like all buttoned up. Notice up there is a serial pigtail above the oil tank for my T-Max, and just beside it is the tail end of a wire sticking out. That tail end is where my single Load Resistor resides, and it is strapped to the underside of that frame where the seat rests. So, why did it not work the way I expected? I went back to the original wiring diagram, and I think I see my problem. I was busy looking at where the wires were going to the turn signals and how they were getting there through the harness connectors. If you'll take another look at the wiring diagram, you'll see that wires are shown fairly far back that split off and go to the instrument cluster.


(Click to SuperSize)


I don't know where in the actual wiring along the spine of the Sportster frame that these wires split off, but it is obviously downstream from the splices I made just past the TSM. That would mean the current going to the running lights now has direct access to that circuit. Further, since the Turn Signal Indicators (TSI) on the instrument cluster light up as running lamps while the LED turn signals do not, I am left to assume the resistance going to the TSI is less than the resistance going to my LED signals. Will I tear it all apart and search this out? Time will tell, but I know I will not be doing this today. You guys have been busy! Well, me too! I wanted to see where the wires went and how hard they'd be to pull out to test my theory about the instrument cluster lights providing the shortest path and ruining my running lights. When I took the wiring off of the instrument cluster, I found that there was no plug under there. The cable goes straight to a tiny circuit board with a few LEDs on there. CRAP! That means the only place to splice must be somewhere in this harness where the factory spliced the wires. (actually, I need to splice those two wires with the white cable tie wrapped around them)


(Click to SuperSize)


Nothing to it but to do it, I always say! (uh, no I don't - in fact, I never say that - but I did today) What did I do? I cut that beautiful wire loom off. If you click to zoom in, you can see where the splices are in the Violet and Brown wires. Two wires go forward (one to the turn signal connector under the tank and one to the turn indicator on the dash) and two wires to backwards (one to the TSM and one to the rear turn signal).


(Click to SuperSize)


The wire to the turn indicator on the dash was snipped, and I added a custom wiring that now goes down that spinal cord to the TSM. It is not wired up now, but it will most likely get wired up next weekend.


(Click to SuperSize)


Here is the final schematic I used to make it all work. You may notice it does not actually show the instrument cluster wired to anything yet. Ha! That's the way it is right now, too! LOL


(Click to SuperSize)


So, how did it turn out, you ask?



I wanted to create a better wiring diagram to explain how to do the wiring on this diode project. I was looking at this pic and thinking I could make the wiring diagram make more sense.

Exposed TSM Wires
(Click to SuperSize)


I created a stock wiring version for LEDs. Pins 3 and 4 of the front connector are not used, just like most of you out there do who run LEDs:

Typical LED Setup

If you want Front Running Lights on your LEDs but not Rear Running Lights, you could modify your wiring in this neck region to be like this:

Front Only Schematic

The front connector now uses power from the Running Lights on pins 3 and 4. The 470 ohm resistor is there so that the LEDs are not working at full brightness. Look closely and you will notice 12VDC power to the Load Resistor from one circuit will not enter the other turn signal circuit because the diode blocks current flow in that direction. This prevents both blinkers from turning on at the same time. Also, the diode placed up front prevents the running lights power from getting to the rear turn signals. If you'd like your LEDs to have Front and Rear running lights (like I did), all you should have to do is this:

Front and Rear Schematic

The only difference here is that you move the front diodes "upstream" of the place where the wiring splits up to front and rear. Now, power from the Running Lights will be on the rear LEDs. Notice that both designs use the single Load Resistor idea. I had to make changes to the images, which should be correct now. I added the Load Resistor (shown in Yellow) and the 470 ohm resistors from the running lights.