- Fri Oct 05, 2018 10:25 am
#79483
What model and year is it? Some run the lights on DC from the battery, others run them on AC direct from the alternator (lights only work with the engine running on these). If you have an AC lighting system, they don't always play well with LEDs anyway.
In any case, it's probably earth leakage. Some of the current earthing to the casquette may be leaking backwards through the LED and finding a better route to earth through the main beam bulb filament. It only takes a few milliamps to make an LED light up.
One solution would be to use a polarity sensitive LED (many are wired to be used in either direction) so current can only travel in the right direction. Another would be to use a small ballast resistor in series with the LED bulb to slightly increase the load in the circuit. Using an actual diode in series with the LED is also an option. The simplest solution is to just use a filament bulb, they are very low wattage anyway.
Something else that may be worth a try (and is sometimes worthwhile anyway) is earthing the front end of the bike with a dedicated wire. The chassis earth at the front of a bike is relying on tohe power finding its way back through the steering bearings which are covered in non-conductive grease. It's not uncommon and certainly not wrong to fit a good chunky earth wire with a ring terminal on each end connecting the front end of the bike to either the main frame, engine or battery negative to ensure good continuity. I always incorporate such a thing when I design a wiring loom along with one joining the engine and frame rather than relying on the mounting bolts.
