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What resistors do I need for brake tail lights? Answered

Hello recently I burnt one of the brake lights and I though why not to use a LED one to replace it.

So I got the appropriate lamps and added them to my car only to realize that now the 3rd brake light on the back also light when I just have the night lights on. Sure it light even stronger (along with the main left and right brake lights) when I brake but this weird behavior scared me a bit, it could be pretty bad if my tampering with the lights result in some electrical problem in the middle of the night.

After a bit of research I see that I need to add resistors to the LED lamps because if the electrical system realize there is lower power draw then it may behave weird.

So the question is what resistor do I look for to add before the LED so the car still believe I get the same power draw?

I drive a hyundai atos prime 2001 and the old lamp says 21/5W on it ( I guess the 21 is for brake light and the 5 for the night light?).

The guy at the store told me to learn ohm and watt so he can give me the right resistor.



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