I recently bought my 2010 XKR and looking to change out the amber bulbs in the headlights for a more modern clean look. My question is the bulb that is in the turn signal now, is a 3457 bulb with 2 filaments. Should there be a dual filament bulb there? From what I have been able to find that bulb is just for turn signal and has no other use for the second filament. Also, it seems that every cross reference I have found including the owners manual shows that the bulb is PY21W, but is is not a bayonet base? Any information on this would be appreciated, so that I do not make the wrong purchase on new bulbs.

Thanks in advance...
Aaron

 

My '07... Dual element bulb with a single function.

https://www.jaguarforums.com/forum/x...4/#post1809451

Personally I like the yellow elements. Think they give a bit of life to all that silvery whiteness.

 

Yes - this has me somewhat confused. I, too, have the 3457ak bulbs in the front turn-signal position despite the user manual showing PY21W's.

What's odd is that the 3457AK's are dual-filament, but clearly only one of the filaments is being used (there are only two wires connecting that bulb and the connector only touches 3 of the four contacts). So I am confused as to why they fitted a dual-filament bulb in a single-filament application.


^^^^ What the owner's handbook says I should have





^^^^ What I actually have

 

That is actually a DOUBLE-TWO CONTACT base. They are designed that way so they are impossible to place backwards. Flip that bulb over and the contacts are all in the same relative position, so it doesn't matter which way the bulb 'faces' when installed, the contacts will always be in the correct position. That said, it makes no difference which way it faces, either or both elements will illuminate regardless of the position, unlike the lamps with different wattage filaments. I don't know why two filaments, as there is no way to differentiate between the two with that base design. Maybe because the MUX BUS (or whatever it is) sends different voltage through each contact?

 

Yes - I noticed that the base/bulb contacts are set up so that the same filament will light regardless of which way the bulb is placed.

Still seems odd to me that a two-filament bulb is used in a single-filament application. But hey - who am I to judge? :-)

 

I haven't heard anyone say "mux bus" since I worked on jets in the Marine Corps about 30 years ago.