Info on resistors, trying to change voltage from wire

Hello everyone! Story (skip below if you don't care): I'm trying to fix my rear tail light on my motorcycle. The running light wire became corroded or disconnected somehow. What I would like to do is reconnect it to another wire with the correct voltage on the bike. I tried virtually every wire already and when the bike is running they are all around 12volts, rather than the 9volts ish that the tail seems to like to run correctly (12 volts lights it up like you are hitting the brake constantly)...

So my question I guess is what kind of resistor can I use in order to bring voltage down from 12 volts ~ish to 9 volts ~ish? I found ones with a 5%, 10%, and 20% tolerance but is there something out there with a 75% tolerance perhaps? Not sure what to do. Thanks in advance!!

Most tail lights have 2 filaments, one for the tail light and one for the brake light. Make sure you have the correct filament hooked up.

I do, the wire for the brake light is fine, but the wire for the tail light is inop..

Is the lamp an 1157 type?

The bulbs say 2057LLCHINA on them.

That is a twin filament lamp. Each of the solder blobs on the bottom connect to one filament. The cylindrical part is ground.

Both filaments are designed to run on 12 V. One takes about 1/2 amp and is used for the tail light. The other takes about 2 amps and is used for the brake light. You shouldn't use a resistor for either.

cfdp said:

The bulbs say 2057LLCHINA on them.

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A 2057 draws a current of 0.48A on the smaller filament. Your resistor needs to drop ~3V at 0.4A, so 7.5Ω. It will be dissipating 3*0.4 = 1.2W, so buy a 2W or 5W resistor.

Thanks! I'll try that and let you know how it goes...

Tried a 1watt and 5 watt resistor with no luck. I noticed different wires on the bike have the same voltage output, but differing watt/oam output? I'm so confused but I found a wire to use with two 1watt resistors both in line giving me a slight lower light luminance vs. when hitting the brake, which will just have to do for now..
Started ripping the bike apart to track down the original wire, very confusing where the wire goes.

cfdp said:

Tried a 1watt and 5 watt resistor with no luck....

Click to expand...

What was the resistance (Ohms)?

Not sure I got them from Radio Shack, I can double check when I get home..