Bruce Hubbard

Hi,

My 2014 W212 E250 had a faulty illuminated door sill.
This version of illuminated door sill fitted to the late 2014 SE1 Special Edition Package is stuck down with double sided tape.
You can't prise it up without damaging the brushed aluminium, so be careful.
To remove it, run a box cutter underneath it with slicing action, to cut through the double sided tape.
The plastic will likely crack as you remove it but this will give access to the flex board.
Mark each end of the illuminated door sill with tape before you remove it so that it goes back in the same place.
Remove all traces of the old double sided tape with WD40 to soften it and scraping with fingernail to avoid paint damage.
Clean the WD40 off with turps on a rag, ready for refitting the illuminated strip

The circuit is a zener/transistor series regulator.
Combined zener bias current and transistor base current through the 56 ohm resistor is 15mA
Each circuit draws 35mA from 12v which give 20mA for the LED current.
Three LED's are in series, about 3.2v each driven from about 9.6v regulated.
This circuit is duplicated. The flex board is feno PR120190-BRD
The wires attached are for testing the circuit with a 12v power supply

The LED's crack with heat and water ingress and with age and will flicker off and on, and 3 pcs being in series it only needs one faulty LED
Remove all 6 LED's and replace with OSRAM 3.3v White LED side view SMD part number LW-Y1SG-BFOO-GKJM-1
RS Components Stock number 224-9971 25 pcs on a strip for about $20 plus postage
Remove the old solder with solder wick, and clean all the flux off the flex board with Servisol Electronic Circuit Board Cleaner from Jaycar
All of the LED's need to be straight in line to interface with the clear plastic diffuser strip
I chose to tape all the broken pieces of yellow plastic together to allow rework in the future if it fails again
The tape I used was Officeworks PPS masking tape 18mm wide. It is very thin 130 microns to sit flat on the yellow plastic broken pieces
Cut a 5mm wide strip of tape, and with the diffuser in place, butt the flex board LED's up next to it, and tape the back of the flex strip to the diffuser

Fix the completed illuminated strip back in place on the door sill using silicon
My car is black and I used a small tube of Monarch mini gap filler 240g which is water clean up.
Clean around the edges of the illuminated strip with a damp sponge and rag.
Use some tape to hold down the illuminated strip for 24 hours while the silicon hardens

Just like new, only better. Now water can't get under the illuminated door sill and damage the flex board and components

CaliBenzDriver

Bruce, that's really good digging 👏

Why not replace the discreet zener regulation with one or more 3.3V regulator... it's the ARM CPU supply voltage, found cheap all over. Stable in temperature, load current and input variations (14.9V! Max?)

I grew up on 1/2W zener diodes and bipolar 2N3055 regulators until the 7805 showed up and reverse 7905 too - What a deal that was 50yr ago already!!
There were no CPU, nor consumer software nor buggy CAN-Bus modules -


Any pics of these nice sills?

++++ I have the luxury sills for illiterates owners... ✌️​​​​​​

Chevota

I don't suppose you know where the power wires go? Because I want my sills Off and I don't want to go through all that to pop them off. It would be nice if there was a plug conveniently located elsewhere.

Bruce Hubbard

Just lift up the carpet next to the door
Trace the cable along and you will find
there is a plug and socket there
and you can disconnect power to the door sill