HOW TO Change Backlight on Headlight Switch W124

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Active Member
Dec 15, 2006
Up North
1994 E300D 24 valve - 1991 300D with 210k (retired) and a White Transit Van
1994 W124 E300D
I did quite a lot of searching on this subject and nobody seemed clear if a W124 had back illumination around the headlight switch and headlight sinker/raiser or not. Well I can tell you at least mine does.
This is how they are changed

First of all get a good grip on the actual knob/switch and gently but firmly pull towards you. Be careful as there is a small bulb in the end of the threaded bit (A) this is the bulb that shows orange when your fog light is blinding the poor sod behind you.
Anyway when you have that off you will see a large nut. I am told an 18mm socket will undo this, so undo it.........

Then using a flat head screwdriver or something similar slowly lift and push and lift where the number 1 is (or there abouts) and the facia will come away.
Don’t yank on this too hard cos the small backlight bulb (A left) will be in the housing (Z) and you don’t want to damage that or the cables so Gently Bentley.
The cable connector going into the housing (Z) will come free with a little pressure – pull and waggle. Once it’s out replace the bulb. If you want to test them before you put it back together just push the switch back on and see if everything works but make sure nothing can short out or you will be going behind the dash to change the fuse.

When you put it back together make sure that the left hand tab (X left) is put in first when you see it you will know why, push in X right then re-fix the 18mm nut push the selector back on, all being well you are now illuminated.

Correction propagated: you need a 24mm socket, not 18mm. Sorry!

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