Rear turn signal light bulbs

[bxs]

Subject: Rear turn signal light bulbs

I note that the two rear L&R turn signal light bulbs are dual filament type 1057s. The official Owner's Handbook states that are 12v 21/5 meaning 21 watts & 5 watts. When the turn signal is activated only one element light flashes.

So why are there two filaments in these bulbs I ask?

[TorqueHorse]

I can't remember exactly, but I think since it is both a Tail and Turn light, it will have different brightness depending on if your lights are on and if you are applying the brake?
I remember backing up to a dark glass storefront one night and trying every possible combination of lights while looking at the reflection. There is quite a lot going on back there

[bxs]

Thanks @TorqueHorse ... You are correct about that ... and yes the two filaments are for side running light 5 watts, and 21 watt for the turn signal.

[Tuga2112]

do you guys have red turn lights ?

in the UK dual filament bulbs are used for sidelights and brake. single 5w being the sidelight and the 20w filament used when braking.