Page 1 of 1
LED rear light problems.
Posted: Sun May 14, 2017 5:24 pm
by Torsen
Hi. Change my rear lamp to a caferacer LED lamp.
But got problems with light. Its normal under selfchech when I turn ignotion on. After 2 sec its to bright. Close to the brake light. Do I need some modifications?
Re: LED rear light problems.
Posted: Sun May 14, 2017 9:04 pm
by towerworker
Generally when you replace the stock "incandescent" bulb with an LED replacement you also install a resistor that fools the electrical system into thinking you have a stock bulb. And that's because the LED pulls a small fraction of the current that the stock bulb uses. So the electrical system thinks you have a blown bulb back there and it behaves differently trying to ensure there is some sort of brake light. BMW cares about your safety and wants to make sure people see you and don't rear end you! I would think the light you are installing would have some provision for that. (If it was specified for your particular bike)
Years ago I installed a "BRAKE!" led replacement. (sadly they are no longer in business). Incredible system. Inserts thru the stock light socket and fastens inside the red lens assembly. It has a programmable flashing feature and after flashing for the length of time that's programmed it then burns steady. Along with that system was a long ceramic wire wound resistor. That resistor upped the current draw to mimic the stock bulb. Then the BMW electrical system was happy and allowed the brake light to function as programmed.
Re: LED rear light problems.
Posted: Tue May 16, 2017 6:15 pm
by Torsen
I fix it. Added a resistor to the rear negative light wire and grounded it.
Re: LED rear light problems.
Posted: Thu May 18, 2017 2:56 pm
by lcarlson
towerworker wrote:Generally when you replace the stock "incandescent" bulb with an LED replacement you also install a resistor that fools the electrical system into thinking you have a stock bulb. And that's because the LED pulls a small fraction of the current that the stock bulb uses. So the electrical system thinks you have a blown bulb back there and it behaves differently trying to ensure there is some sort of brake light. BMW cares about your safety and wants to make sure people see you and don't rear end you! I would think the light you are installing would have some provision for that. (If it was specified for your particular bike)
Years ago I installed a "BRAKE!" led replacement. (sadly they are no longer in business). Incredible system. Inserts thru the stock light socket and fastens inside the red lens assembly. It has a programmable flashing feature and after flashing for the length of time that's programmed it then burns steady. Along with that system was a long ceramic wire wound resistor. That resistor upped the current draw to mimic the stock bulb. Then the BMW electrical system was happy and allowed the brake light to function as programmed.
I've got the BRAKE! module, and it is indeed a great product.
Re: LED rear light problems.
Posted: Wed Jun 14, 2017 7:13 am
by Torsen
Now the red triangle light lights up because of the rear led breaking light. Any solution?
Re: LED rear light problems.
Posted: Wed Jun 14, 2017 1:09 pm
by towerworker
Torsen wrote:Now the red triangle light lights up because of the rear led breaking light. Any solution?
I'm guessing the system still thinks there is a bulb failure because of a difference in measured current. Is the brake light working properly?
If it is you might need to possibly use a resistor of slightly more "resistance". Can you contact the light manufacturer of what you installed? Possibly they have a solution. I feel pretty confident though that the added resistor is not the needed value.