Car bulbs..

skunkwerx

Weird this. 

My Megane has a tonne of frikkin bulbs, 
but on the rear there are 2 dedicated reverse bulbs, 2 indicators obviously and 2 dual filament brake and tail bulbs. 

It also has another pair of tail lights that are dual filament, these are tail lights and rear fogs. 

Usually I check the manual, pull the bulb and replace the pair easy. 

The manual says p21/4w. 
The bulb in there already is indeed just that. 

So on to halfrauds site, check the reg to make life easy and find the bulb number, yet it says p21/5w.. 
Infact every online bulb outlet states that. 

I did find what should be the correct bulb, a p21/4 with offset pins.. so I’ll pick some up on the way to work. 

What gives? Can a seemingly more popular  21/5 be used even though the manual says 21/4? 

Thats if to say I get down there and find the 21/4’s are somehow not going to fit. Doubt it though. 

Never had these inaccuracies on the old focus.. ah how I miss it.  Though its sidelight bulbs constantly melted the headlight surrounds.. actually I don’t miss it. 

Emp_Fab

I believe the P21 part relates to the fitting and the 4/5W part is simply the bulb's wattage.  You won't have any problems interchanging a P21/4W with a P21/5W.  One will be fractionally brighter than the other.  Apart from that, there's no difference.

m_c

The P indicates the type/size of fitting, but not the contact/locating pin configuration.

The numbers are the wattage, in this case 21W for the brake light, and 4W or 5W for the tail light.
Although 21/5 are the most common, certain models have used 21/4 with offset pins so you can't install the wrong bulb.
IIRC certain VW Golfs also used 21/4W bulbs.

It's one of these things seemingly strange things that gets done to meet some obscure light output regulation.

skunkwerx

Its doubly weird because when I checked, the other 2 bulbs right next to these combined tail light and fog lights are my other two tail lights and combined brake lights.. which guess what, are 21/5! 

Never noticed before, weird, they could have just used the same bloody bulbs!! 

Anyways all sorted, couple of quid for a bosch double pack of 21/4’s. 

I wonder if they intentionally did it so that the outer tail lights are fractionally brighter than the inner pair, some kind of styling feature maybe... 

m_c

It's French. If you ever spend anytime in the motor trade, you soon learn not to try and understand French reasoning.

My favourite is still Renault truck engine timing. Not only do they number the engine the opposite way from everybody else, they then decide to pick cylinder 3 for timing purposes.

skunkwerx

m_c said:

It's French. If you ever spend anytime in the motor trade, you soon learn not to try and understand French reasoning.

My favourite is still Renault truck engine timing. Not only do they number the engine the opposite way from everybody else, they then decide to pick cylinder 3 for timing purposes.

Haha, man I’m finding out... 

I spent ages trying to find a definitive location for the cabin filter.. turns out it could be in 1 of 2 places..
That was part 1.. 

Part 2 was taking a guess and then getting to either place.. 
Either its on the left requiring half the dashboard to come out, or on the right requiring the clutch to be removed.. 

Why couldnt they just make a flap under the dash for it lol!!