Turn signal wiring

[Skinner]

Of all the maintenance issues due these bikes, electrical is my weakness. That said, I have some new front turn signals for my 82 Kat. The original ones have 2 wires, the new ones have 3 - red, black and black/white. They are simple EBay units - any ideas what the third wire would be for? I'm assuming it has something to do with grounding, but I may be wrong.

Cheers!
K

[Rust_to_Redemption]

I think it is pos/neg and one for powering it as a “running light” or “always on”.

[Steve]

The black/white would be your ground wire. On the stock bike, that would have been a large ring terminal held on by the nut that held the turn signal to its mount on the headlight ear.

You will have to experiment a bit to see the function of the red and black wires, but one should be the lower-power running light, the other will be the higher-power turn signal.

Because these are "simple eBay units", I will have to ask a question or three.
1. Are they incandescent bulbs or LEDs?
2. If they are incandescent bulbs, are they stock equivalents?
3. If they are LEDs, did they come with built-in load compensation?

The stock flasher unit is thermal-based, meaning that it needs to 'see' a certain amount of current to heat a bi-metallic strip that flexes to interrupt the circuit and make the lights blink. Lower-power bulbs (typical in some cheap units) don't draw enough power, so the flasher will not work. LEDs definitely don't draw enough power, so they won't blink, either, but some of them have built-in compensators, so they work normally. In either case, you can change the flasher unit to one that will flash with lower current draw, but if you have self-cancelling turn signals, you will lose that function. In fact, you will also have to do some minor re-wiring of the flasher socket to handle the new flasher.

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[Skinner]

The black/white would be your ground wire. On the stock bike, that would have been a large ring terminal held on by the nut that held the turn signal to its mount on the headlight ear.

You will have to experiment a bit to see the function of the red and black wires, but one should be the lower-power running light, the other will be the higher-power turn signal.

Because these are "simple eBay units", I will have to ask a question or three.
1. Are they incandescent bulbs or LEDs?
2. If they are incandescent bulbs, are they stock equivalents?
3. If they are LEDs, did they come with built-in load compensation?

The stock flasher unit is thermal-based, meaning that it needs to 'see' a certain amount of current to heat a bi-metallic strip that flexes to interrupt the circuit and make the lights blink. Lower-power bulbs (typical in some cheap units) don't draw enough power, so the flasher will not work. LEDs definitely don't draw enough power, so they won't blink, either, but some of them have built-in compensators, so they work normally. In either case, you can change the flasher unit to one that will flash with lower current draw, but if you have self-cancelling turn signals, you will lose that function. In fact, you will also have to do some minor re-wiring of the flasher socket to handle the new flasher.

.

Hi Steve,

Thanks for the reply. They are incandescent units, same wattage as the bulbs they are replacing. Even though electrical is my weakness I've read enough on these forums to know installing LED's is not usually a simple swap.

These are installed on the Katana's fairing, not the headlight ear, so there is no metal grounding point.

[Steve]

Did the stock lights have a "running light" function? That would be the dimmer "marker light" function, similar to your car.

What colors were the wires on the stock lights?

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[Skinner]

Did the stock lights have a "running light" function? That would be the dimmer "marker light" function, similar to your car.

What colors were the wires on the stock lights?

.

No running lights. Black and black/white.

[Skinner]

So I sent 12 volts through all of the various wires on the turn signal. Black and black/white is very bright, like it should be. Red and black or red and black/white also lights up, but not nearly as bright, which leads me to believe that it's a "running lights" circuit. I'll just wire it up with black-black/white and leave the red capped and see how it goes.