rear blinkers getting power

hi everyone, that's my first post here in 6 years of ownership, i really hope i can get some advice as couldn't find the answer anywhere:

after changing rear blinkers to LED i noticed that they glow when they are off, even when bike is off. apparently there is 8V coming there all the time and only to the rear ones, it just wasn't obvious with lamps as they remained off under that low voltage.

another strange thing was that sockets for computer connection and connection for USB plug have (-)11V on them regardless if engine is running or not, accordingly they could not power anything.

any ideas, fellas?
eugene

LEDs require suitable resistors in parallel with them, to fool the system otherwise they will report a blown bulb. My suggestion is 15Ω, 5 watt. The 1200 8V has individual connection from the dashboard, so if you have fitted them front and rear you will require four of them.

As for the -11v, perhaps you have your meter leads swapped? Can't fathom how else you can find -11v.

Thanks for prompt reply.
I get resistors fitted with them but it still got constant 8V coming there when everything is off. Once on - it comes full 12V on and off.
Nothing coming to front ones although you mentioned there is separate connection...
Does ECU software have anything to do with that, just suggestion?

As for -11V on the plugs- meter is fine and shows right elsewhere. That -11V remains steady whether bike is off or on. Neither GPS nor USB plug take it. I could understand if there was 12v and wires were mixed up but 11v..?

Because of the very high input impedance of multimeters (especially digital ones), they can get fooled by minute spurious voltages that might be around. Hang a small wattage 12v light bulb across the input in parallel with the circuit being measured and see if this changes anything.

thanks for your note, mate but unfortunately the problem is not in there b the way it looks:
the multimeter is not digital and quite high quality, with the original bulbs in parallel or resistors there is 8v power present when everything is off unless i pull the main right fuse out.
oficial dealers couldn't help that either.. must be real italian bug

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There is something odd going on, the lamp hot side is well grounded through the incandescent lamp.
Perhaps the common ground is not connected properly letting the lamp float above ground.
(after all the front is wired the same way and its no problem)
I don't know why it should float so high but perhaps there's a high impedance resistor pulling it up.
For instance the resistor that triggers the blown lamp alarm, it would trigger the alarm if the filament is not holding it down.
I would double check the lamp ground connection.

I'm not sure what you will need to do to run LEDs, perhaps just a small load resistor e.g. 100 Ohms, just enough to counter the blown lamp resistor.

thanks, Roy, thanks everyone.
that power is present at the coupling under the tail and to chase it further would mean ripping through the whole harness, i'd try to avoid it by all means although got my hands itching to do ust that.
so far the change of the resistors for higher wattage - 20W/10ohm solved the problem with glowing although i still might be drawing battery so will have to watch out for that.
really appreciate your care - good to know there is someone out there

I know it's a different scenario as you shouldn't now have any bulbs in the circuit but saw this the other day (whilst looking for a rear light for V50 project) and reminded me of your problem....just a piece of info, not suggesting to buy one !

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thanks for the thought. i had this in mind but thought resistors should have worked that out.
have a good one

With vehicles, I would advise on using 1000 volt diodes - doesn't hurt to have overkill, and save the things going bust. Probably not as applicable on motorcycles, but with auto electrics now getting into the 40 v - 60 v range (or even higher with electric propulsion) planning for the worst case, means there is a decent margin of safety. Just keep it in mind...

I told Eugene I would get to the bottom of this, it was a beautiful sunny day so I ran the GRiSO out into the driveway.
First off I removed one of the rear lamps, its a standard incandescent and measures 1.4 Ohms when cold. When I turned the ignition on without the lamp in place the dash threw up a bad lamp alarm. It does this as soon as the key is On irrespective of where the indicator switch is.
As I suspected there is a very small current pulling the Dash Input/Output (lamp wire) high. This current measures just over 40 microamps and its there whether the key is On or Off.
Without the lamp the open circuit Voltage goes to 11.2 Volts (key on or off)
If the output line goes above 3.2 Volts the Dash will trigger the alarm graphic and turn on the red triangle.
I tried a few resistors across the lamp holder  to see what effect they have
100K Ohm is too large, the alarm stays On
1K Ohm pulls the open circuit Voltage down to 0.04 and turns the alarm Off, I also tried 2K and that also kept the alarm Off at 0.08 Volts
This is good news as the 10 Ohm resistors others were advocating are huge.
..............
I converted one side of the bike to LEDs using some lamps I have, these worked fine without shunt resistors, there were no alarms.
The lamps I used are 19 LED clusters with a forward Voltage of 1.97 Volts (obviously all the LEDs are in parallel)
Other LEDs may have a different forward Voltage e.g if the LEDs are connected in series. This would mean the forward bias Voltage would be higher, perhaps enough to trigger the bad lamp graphic.
..............
Conclusion:
I believe any 12 Volt LED will work with the GRiSO dash, you may or may not need a shunt resistor depending on the lamp configuration.
Your GRiSO doesn't need the huge resistors that a thermal flasher relay need.
..............
Recommendation:
If your bike throws up alarms with LEDs solder a 1K resistor directly across the lamp holder contacts, this will hold the Voltage down below the alarm trigger point. There is plenty of room in the OEM indicator lamp holder for the small resistor. No need to insulate it as the surrounding parts are plastic.
A 1K resistor will dissipate only 0.144 Watts so 1/4 Watt is adequate. I'm sure you could go much higher in resistance but there is no point 1K is a very easy size to find.

BTW This open lamp alarm will have a small residual current 4 x 40 microamps because you cannot turn it off (this is perfectly normal) but compared to the battery this is insignificant.
I hope you can understand this, if not please throw some questions my way.

Hey Roy,

Credit to you for taking the time and effort to solve another electrical mystery and will hopefully fix Evev’s problem. sound man

To bring this full circle.

evev wrote:

hi everyone, that's my first post here in 6 years of ownership, i really hope i can get some advice as couldn't find the answer anywhere:

after changing rear blinkers to LED i noticed that they glow when they are off, even when bike is off. apparently there is 8V coming there all the time and only to the rear ones, it just wasn't obvious with lamps as they remained off under that low voltage.

another strange thing was that sockets for computer connection and connection for USB plug have (-)11V on them regardless if engine is running or not, accordingly they could not power anything.

any ideas, fellas?
eugene

Some LEDs light up with an incredibly small current 40 microamps in this case, the 1k resistor across each lamp will take care of that. The front lamps will be lighting up as well although if they are a different colour may not be as noticeable.
This tiny leakage current has always been there, the incandescent lamps just didn't show it.

I installed 4 15 ohm 5 watt resistors and I'm still getting the flashing error messages on the dash.
Thoughts or comments?
Regards

You don't need 15 Ohm resistors a 1K 1/4 Watt across each lamp holder is all you need.
You need to get the Voltage across the lamp down below 3 Volts to turn the alarm off.
If it still lights at all you can decrease the resistance to say 330 Ohms, that should put it out for sure.

A normal incandescent bulb has a low resistance holding the Voltage low but an LED because of its high forward bias won't hold it low
I proved that a 1k resistor across the lamp will easily hold it below 3 Volts (In parallel NOT series)

Here is the way I see it. Each of the flasher outputs has a 40 microamp supply trying to pull the output towards 12 Volts
If its able to pull the output higher than 3 Volts the dash throws up a bad lamp alarm.
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Incandescent lamps being low resistance hold the output low unless the filament burns out in which case the output will pull up to 11+ Volts.
LED lamps however have a high forward bias Voltage (they dont start to conduct until the Voltage is quite high)
The easy fix is to make the LED low resistance by adding a 1,000 Ohm resistor in parallel thus holding the 40 microamp current near zero Volts

Thought that i was good at bike Electrics till i read Kiwi_Roy
time to go back in me hole