A 380 bulb is a twin filament bulb whereas a 382 bulb is a single filament bulb, so you'd have thought it'd be a 382 if the only job is the brake light.

Unless it's a failsafe system, if the led light fails then the 5w part of the 380 bulb illuminates?

Or they just fit the same bulb & bulb holder as the standard non led lighted Focus with no with wiring to the 5w part for cost reasons.

 

Or they just fit the same bulb & bulb holder as the standard non led lighted Focus with no with wiring to the 5w part for cost reasons.

This sounds like the answer

 

@Gareth350, thanks, that makes sense. Probably more of a cost cutting exercise, knowing Ford.

 

It's like my daily Corsa, 2 reverse lights that both work & 2 fog lights, but only the os foglight has wiring to it, there's even a bulb in the holder on the non wired ns!

 

So which upgrade lamp/bulb did you order?

The 382 (P21W) has only one contact pin, whereas the 380 (P21/5W) has two.

 

I ordered 380, as per the Autbeam website. The ones in the car are also twin contact 380’s.

The MK3 though has separate led rear side lights, so ’m trying to find out, apart from brake light, what the original 380 does?

 

I would say Gareth's guess above about common parts for LED/Non-LED tail lights is close to the truth.

I know we had problems with the early LED'S on the Mk2 due to the wiring polarity, but I can't recall seeing this issue previously.

I had a quick look at the Autobeam and Osram websites and both list the P21/5W as being the correct fitment.

Strange...

 

@Andy, thanks mate. That’s exactly what I thought. I even thought that maybe the 5w filament was perhaps for parking lights, but no…they operate the led side light bar too.

 

I wonder if it's to do with emergency braking light. On Mk3 s if you are driving at high speed and have to apply brakes in an emergency the brake lights flash on/off very quickly so it may use the other filament. If you watch a Mk3 on race track you will often see this braking into corners at end of high speed straight.

 

@Steve-RS that could indeed be what the other element is for, who knows.

 

The unused filament will be the 5w one, not bright enough to act as a brake light, even if it came on at the same time as the proper 21w brake light, you wouldn't see any difference.