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W140 Light Switch Graphics Backlighting

24K views 17 replies 12 participants last post by  Rupununipete 
#1 ·
Hello everyone:

The bulb behind the graphics on my light switch has gone out and I am having a hard time accessing it for replacement. In the attached photo the graphics that I am referring to are circled in yellow. Circled in red are the three screws that I have been able to find. Thing is, I undue all the screws - and nothing. I can't seem to remove the panel, there is no slack for wiggling it off at all.

Anyone replace this before? Tips / Tricks?

Thanks, JD.
 

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#2 ·
Here's the procedure for removing the lower dash and the switch for a '97. It should probably work for you as well:



Air grate (1)
push out with plastic wedge.
Screws (2 and 3)
screw out, hold cover down for access.
Screw (4)
screw out.
Screws (5, 6 and 7)
screw out (8 mm ).
Nut (8)
screw off (10 mm ).
Cover (9)
pull down and remove.
Reinstall
in opposite order.



Preliminary work:
Cover below instrument panel removed.

Quiescent current retention unit
disconnect, connect.

Ground cable at battery
disconnect, connect.

Steering column adjustment control button (1)
pull off, push on.

Locking element of exterior lamp switch (2)
press in with a screwdriver and pull off exterior lamp switch (2), press on.

Bulb (3)
pull out, insert.

Screws (4)
unscrew, screw in.

Covers (5 and 6)
take out, insert.

Screw (7)
unscrew, screw in.

NOTE: Hold adjusting lever (8) with plate nut (9) for the screw (7) to prevent it turning when installing cover below instrument panel.

Nut (10)
unscrew, screw on.

Cover (11)
take off, fit on.

Pneumatic line (12) except with HPF and xenon headlamps
pull off, fit on.

Lighting (13)
withdraw, push in.

Exterior lamp switch (S1)
turn to left and take out downward; insert from below and turn to right.

NOTE: Ensure the retaining lugs (arrow) on the exterior lamp switch (S1) are correctly seated.

Electrical connection (14)
unplug, plug in.
 

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#3 · (Edited)
You almost had it. Just remove the three screws, under the steering wheel control there is two screw and look under the light switch base you will see a small slotted hole that will need to be press in with a small flat screw driver, remove the light switch knob then remove the large nut under the switch knob. This is the only way to change the small light behind the light panel. Its easy good luck.
 
#4 ·
thank you bobs and oldschool. there is a wealth of information here. thank you both for your speedy replies. i almost want to go outside and retry, but think ill wait til tomorrow - during daylight. will follow up upon a successful attempt. best, jd.
 
#7 ·
it's definitely supposed to work. Mine is on the fritz. it'll normally illuminate a few minutes after the lights have been turned on, but almost never right when i turn them on. sometimes it seems as though hitting a pothole knocks it on.

the funny thing is though that the little light, that turns on when the fog lights are engaged, illuminates immediately everytime.
 
#10 · (Edited)
So it worked! Not terribly difficult once you know what's what, but doing this tiny job really exemplifies how 'overengineered' the W140 is. While a similar job in a Lexus probably requires the removal of a mere two screws, there are far too many steps to open this tiny little panel in our MB's.

In addition to removing the three visible screws, note that there are two additional screws hidden behind the steering wheel adjustment switch. The trick when removing the steering wheel switch is to know that the lower portion (blue arrow) sort of clips in, so just put a little pressure upwards and the switch assembly will come out (you have to pull it straight out a little too). Behind there are the two additional screws.

Note also the large blue oval circle. After you remove the two screws there (red circles), hold the parking release out and remove the moulding which the screws were screwed into (it comes out).

As for the bulb behind the assembly, make sure that you actually pull out the wire that the socket is connected to - there is slack to the line - and that you insert it into the panel (that you removed) before you put everything back. What happened was that I replaced the bulb, then put everything back (thinking that there was no slack to the line), but the socket was not properly attached to the panel and while the bulb lit when I put everything back together the light was very dim. After I screwed everything back together - I had to open it up again! You'll see what I'm talking about when you open the panel!

Oh, and dont forget to remove the nut behind the light switch itself! And also, good news! - no need to remove the knee bolster!

Thanks for everyones help.
 

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#12 ·
Thanks for the information guys. I used the guide posted here to replace the two little bulbs on my dash. This was after the mercedes service centre said "No, that switch does not light up, there are no bulbs behind there" :O

Anyway, just a FYI for the guys who want to buy the bulbs from the dealer parts department before they take the dash apart;

Fog light - 12v 5w
Overall Light - 12v 12w.

Thanks again,

Mike
 
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