No turn signals when headlights are on.

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Aug 22, 2005
Well almost. Bike is a stock '73 850 Commando. Blinkers cycle at one second intervals when headlights are off and RPM over 2,000. Headlights on and blinkers go away until about 4,000 RPM or cycle once every seven or so seconds under 4K. 21 watt bulbs. Headlights do not dim when blinkers are lit. Questions; is this normal, alternator troubles, go to a high-output alternator, go to LED signals? Thanks, Theo
Power problem....each of these items uses power. At low RPMs the bulbs, and the motor too, need a certain amount of the battery power to function, as, at low rpms, even a good alternator doesn't produce enough to satisfy all items at once.
Check the battery, see if it is loading too. Cheap voltmeter will do this. Plus to plus pole, neg to neg pole, when she is running,and look for about 14 volts or so...if not, no loading is happening...see if this changes when you give it more gas....if not, maybe the rectifier is busted, or loose wires. Also, work your way back towards alternator and check connections etc, check clearance between rotor and stator too.
By the way...this is not you you don't have to jump to a bigger alternator setup.....until you find why the orginal setup is not working at least.

My guess is that the battery is simply finished (or not getting charged) and the alternator can't , at low speeds, keep up with keeping the motor AND the lights going......if all else fails...wait for the electro gurus to answer your question....
try wiring the headlamp through a seies of relays suplied from a seperate fused wire direct from the battery.

It could just be a faulty flasher relay, they don't last forever.
No turn signals, sort of...

Okay, none of the above. Seems my signals were not loading the blinker properly and the answer was a "load equalizer" from Badlands Motorcycle Products. An old Harley mechanic turned me on to it. Wired into the signal circuitry, the signals blink away without altering functionality of anything else. About $20 too. Thanks for the help, Theo
Do me a favor and explain how this thing works, and why. Aklthough the stock setup works good enough to get by on...I am intrigued.
Am I to understand there is a simple fix that will make the blinkers blink faster, despite the fact that the head light is on and most likely the brake lite too while you are sitting at some red light waiting for the lights to change? I know that when I replaced my rear light with the LED type, the headlight no longer almost went out, every time I used the brakes because the LED used less current and gave more to the headlight to use. Same sort of theory? Fill us in.
Don't know and the instructions offer no explination. I think it either has to be a resistor type thing that loads the blinker circuit or a capacitor thing storing a charge of some kind. But, I've gone from no blinkers when the head light is on to one on/off cycle per second with no diminishing of function in any other lights or circuits. Magic! Their web site is Theo
This will be more than you wanted to know....
The majority of turnsignal relays are not the standard electro-mechanical relay that you would expect them to be. They function by using a bi-metal strip that is riveted on one side and has relay contact points on the other side.
Bi-metal means the strip is made of two different metals that expand or contract as heat is applied or removed. Since the two metals expand at different rates this cause the strip to bend. This can be used in two ways, in the case of a thermal shutdown, the strip recieves the heat externally and then breaks the contact (until it cools down). In the case of the turnsignal, the strip has mild resistance to electrical current and heats up when enough current passes through it. When the strip bends the electrical contact is broken, and now it can cool off, which causes it to return to the original position which closes the contact again.

So it's the current through the lightbulb that makes the turnsignal relay work. And since the LED's use so much less current, the relay will not function properly. What some have done with the 'load equalizers' is to shunt enough current around the LED to make the relay function properly. So you have gained the benefit of a brighter light, but you have not saved any electricity. (Personally I want both benefits for spending the money and effort)

Under the standard configuration the LED is effective for your running lights and brake light. But for LED turnsignals, other modifications are required. Oh, and don't forget, this only applies to negative ground systems, unless you have a LED that lets you internally reverse the polarity (haven't seen any).

Maybe Mr bulbsthatlastforever could be talked into manufacturing an electronic relay. There's a simple schematic on an Austrailian electronic website, but the MOSFET needed is not available unless you buy a couple hundred of them.
How very kind....I begin to get the idea. My background includes 15 years of large radio systems and satilite ground I have a bit of electronics...besides what the various vehicles I have owned have taught me.....but this LED thing is a bit of a side path for me and it is good to get the lowdown.
My baby had a long time when the blinkers wouldn't work very well when stopped at a corner/light And most of it was solved by simply replacing the ancient battery which couldn't manage to hold a charge for a week...just a real pain when you pulled the bike out for a weekend drive. Boyers have to be well supplied with power to get even a kickstart 750 to come to life. My problem was added to with the fact that I run a loud buzzer on the blinker circuit.....too many close calls with a forgotten blinker left on. So the load on the use of the blinkers was quite heavy but all fixed by just replacing the battery. After reading the, what seemed like, too many reports of forum members getting rearended earlier this year, I popped for an LED kit fro bulbs forever. Failure to adhere to normal rules of not clamping wires between two surfaces led to me toasting the board...most expensive piece of toast I have even eaten....but I hotwired around the burned sections of the board and she works like a charm now. Improved the headlight brightness and no more disapearing headlight when I use the brake pedal. I have the normal blinker bulbs....and some blinker relay I bought out of a auto parts store...universal I can't say which type it is...bimetal or mechanical...but I swear the blinkers not only go real nice and fast, despite the buzzer and its current draw...but that they are brighter. That may be simply illusion, but it seems so to this satisfied customer.
If I digested your lesson in electronics correctly, I wouldn't need this item that cascade theo has installed anyway, as I have no LED blinker lights. Mine work wonderful now I was mostly interested in how and why such an item might work. I can understand now how mine might not need this aftermarket item, but why did he need one, and why wouldn't his normal setup just function like mine did..he didn't have LEDs either, as I read his posts. Wouldn't just trying a few different relays have solved the problem...or is this all beyond me?


"as I read his posts" god...been here too long..had to correct at least ten places where I has formulated the sentence as you would in is life there anyway....I haven't been "Home" for over ten years.......might be about time. :lol:
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