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DIY: How to Halogen to Facelift LED Taillight - Season 2
Let's convert the old non-Full-LED(aka Halogen) taillight to facelift(2019+) Full-LED taillight. This procedure is not a shortcut. You need to install 4 new wires from the rear SAM to the taillights.
Materials:
Full LED Taillights, left & right (Facelift, 2019+) (MB Part#: A205 906 5003, A 205 906 4903)
10 Pin Taillight Connector (2 EA) (17 EA pins of 1.8mm x 1.8mm x 13.7mm outside, 0.63mm x 0.63mm inside)
Dupont connector female pins (2 EA) (1.8mm x 1.8mm x 16mm outside, 1.2mm x 0.6mm inside)
Crimping Molex Tool
20 or 22 AWG Stranded TXL Wire (10ft x 4 EA)
Friction Tape (Harness Tape)
Tools: 8mm deep socket, T40 star bit, flat head precision screw driver set, utility knife.
Software: Windows 10 x64 Notebook, J2534 PassThru or SD C4, Xentry 2021.x~, DTS Monaco 8.x~
Estimated time to finish: 4~5 hours Required skill level: mechanical - entry(1/5), electrical & crimping pins - entry(2/5), software variant coding - skilled(3/5). Where to get the material:
Taillight: Mercedes dealership. I paid $440 total including two taillights + shipping.
Connector: Taillight connector is available on ebay/aliexpress but the rear SAM HD connector pins are not (or I couldn't find it). I purchased all from a distributor but they might have wanted to sell 20000+ instead of 2ea. I don't know if Mercedes dealerships have the pins.
Other tools: If you don't have a crimping tool, it's available on amazon for $15~. I recommend open barrel type. Friction tape is $9 on amazon. Automotive wire is $10~$25 on ebay/amazon (don't use PVC jacket wire).
Variant coding: Variant coding means "changing parameters stored in the control module". "Coding" doesn't mean "programming" but means "changing parameter". Have you ever change a setting on the control panel in Windows? It's the same. To change the parameters in the rear control module for the taillight (we call it "rear SAM"), you need a laptop running Windows 10 x64, SD C4 or PassThru device (there are many tools on the market), and DTS Monaco 8.x(software developed by Softing, Inc). Study the software for a while (days). Then, you can understand the procedure on the pdf file attached here.
Pros: It runs as factory installed. No shortcut. Cons: It's only for DIYers for fun. If you hire someone for this, it will cost $$$ at least.
Note: If you buy EU/ROW taillights (amber turn signal), amber turn signal will blink instead of the red brake lights (See: variant coding)
This information is free for all of us. You can share it for free but don't sell it for money.
(Update: pdf updated for more information) (10/30/2021)
For people who want to know the factory retrofit procedure, TSBs are attached here along with the wiring diagram in the MB's WIS. The factory TSB uses scotch lock quick splices to jump the wire, but it will fail in future.
(Update) It has been working perfectly as expected. As I could sell the old taillights for $200, I spent total +$250 for this upgrade.
Originally Posted by Stealthy17
What if you’re updated from 2017 Full led taillights to 2019 OEM taillights?
2017 full LED tail light has a side marker signal but 2019+ doesn't. The pin assignments are also a little different in 2019+ model. But I guess it will work.
(Update) It has been working perfectly as expected. As I could sell the old taillights for $200, I spent total +$250 for this upgrade.
2017 full LED tail light has a side marker signal but 2019+ doesn't. The pin assignments are also a little different in 2019+ model. But I guess it will work.
Running the 2019+ tails on mine now and throwing messages for left and right side markers. Might be able to add resistors to solve that issue or just live with clearing the message. Not a fan of the third brake lights staying on with the c shape LEDs.
Did you solve that issue repinning the connectors or was coding involved. Was looking at your earlier post about W205 Facelift 2019 taillight when on/off and was curious. So I went to carmax the other day to borrow a 2019 to find out how the lights work.
Running the 2019+ tails on mine now and throwing messages for left and right side markers. Might be able to add resistors to solve that issue or just live with clearing the message. Did you solve that issue repinning the connectors or was coding involved.
I did coding as I upgraded from half LED(aka halogen) to full LED. It's easy to turn off a warning message if you have a right equipment/software or can find someone else who can do it for you.
Originally Posted by Stealthy17
Not a fan of the third brake lights staying on with the c shape LEDs. Was looking at your earlier post about W205 Facelift 2019 taillight when on/off and was curious. So I went to carmax the other day to borrow a 2019 to find out how the lights work.
The 3rd 2nd brake light works also as a parking light. It's turned on when you park the car. So you may need a helper to check it or record video with your smartphone.
When you drive => All brake lights off (1st & 2nd & 3rd off)
When you brake => All brake lights on (1st & 2nd & 3rd on)
When you park => 2nd (HGB) brake lights on (1st off, 2nd on, 3rd off)
When you park and brake => All brake lights on (1st & 2nd & 3rd on)
Last edited by realeric; 07-28-2022 at 12:48 PM.
Reason: (correction. 3rd <-> 2nd brake light)
I did coding as I upgraded from half LED(aka halogen) to full LED. It's easy to turn off a warning message if you have a right equipment/software or can find someone else who can do it for you.
The 3rd brake light works also as a parking light. It's turned on when you park the car. So you may need a helper to check it or record video with your smartphone.
When you drive => All brake lights off (1st & 2nd & 3rd off)
When you brake => All brake lights on (1st & 2nd & 3rd on)
When you park => 3rd brake lights on (1st & 2nd off, 3rd on)
When you park and brake => All brake lights on (1st & 2nd & 3rd on)
Understood, as you had to program the rear SAM for LEDs vs halogen. Since I have full LEDs that part is okay to skip. I assume your 3rd brake light still operates as described above?
Before I start buying equipment and going down the rabbit hole of variant coding, is it possible to turn the 3rd brake light off as a parking light?
Started car with main headlight switch on and propped an ice scrapper against the brake pedal and observed the following.
Preface lift
No brake + no turn signal + main headlight switch OFF = brake 1 OFF, brake 2 OFF, brake 3 OFF
Brake + turn signal + main headlight switch OFF = brake 1 ON (blinking), brake 2 ON (blinking), Brake 3 ON (blinking), C shape LEDs ON (blinking)
No brake + no turn signal + main headlight switch ON = brake 1 OFF, brake 2 OFF, brake 3 ON
Brake + turn signal + main headlight switch ON = brake 1 ON (blinking), brake 2 ON (blinking), brake 3 ON (no blinking)
Brake + rear fog + main headlight switch ON = brake 1 ON, brake 2 OFF, brake 3 ON
Brake + rear fog + turn signal + parking light ON = brake 1 ON (blinking), brake 2 off (no blinking), brake 3 On (no blinking). Throwing error message for turn signal/ hyperflash.
Facelift
No brake + no turn signal + main headlight switch OFF = brake 1 OFF, brake 2 OFF, brake 3 OFF
Brake + turn signal + main headlight switch OFF = brake 1 ON (blinking), brake 2 ON (blinking), Brake 3 On (blinking) C shape LED OFF
No brake + no turn signal + main headlight switch ON = brake 1 OFF, brake 2 OFF, brake 3 OFF
Brake + turn signal + main headlight switch ON = parking light ON, brake 1 ON (blinking), brake 2 ON (blinking), brake 3 ON (blinking)
Brake + rear fog + main headlight switch ON = brake 1 ON, brake 2 ON, brake 3 OFF
Brake + rear fog + turn signal + main headlight switch ON = brake 1 ON (blinking), brake 2 ON ( blinking), brake 3 ON (blinking).
Left turn signal on
rear fog on
Update: In your previous thread, you mentioned facelift brake lights are sectioned in 3. 1 being pin 4, 3 being pin 6 (although the image below shows 3 as the inner brake light. The wiring diagram has lower inside light listed as pin 5. Not able to find brake 2 on wiring diagram. So maybe 1 and 2 are shared?) Brake 3 pin 6 lower outside turns off on the new tails with fog light on. On facelift, it’s the inner lower taillight or pin 5 that turns off. So, really 3rd brake light isn’t working as a parking light. That would be pin 5, which I think is the lower led on the pre face lift tails. Since only the upper and lower LEDs work as running/ parking lights.
Since pin assignment is different for pin 5 and pin 6. Maybe move pin 6 to pin 5 location so the lower inner light works as brake 3 and turns off with fog light on. Brake 1 pin 4 works as the upper brake light on both pre and facelift tails, maybe run a jumper wire to pin 6. Trying to figure out the turn signal errors message with fog light on 🫤 Not sure if variant coding can change pin assignment.
Last edited by Stealthy17; 07-28-2022 at 12:06 PM.
Since pin assignment is different for pin 5 and pin 6. Maybe move pin 6 to pin 5 location so the lower inner light works as brake 3 and turns off with fog light on. Brake 1 pin 4 works as the upper brake light on both pre and facelift tails, maybe run a jumper wire to pin 6. Trying to figure out the turn signal errors message with fog light on 🫤 Not sure if variant coding can change pin assignment.
You could be right. Fog light(#8) needs 10 cm (4 inch) clearance from the brake lights. So,
(After 2019) #5 should be turned off, not the #6
(Before 2019) #6 should be turned off
In the variant coding, there is an option; BC_R222(Rear SAM) / [096] OLC Bremslicht Schreiben (OLC Brake Light Settings) / PLSM_Deakt_BLbeiNSL (Turn off brake lights X when rear fog light is on). But the options are only "Brake 1", "Brake 2", "Brake 3", "Off". There is no option for HGB. Pin #5 is connected to not the Brake 2 but HGB. So I guess it's not possible to switch the two pins with the variant coding.
You may switch the two pins (#5 <-> #6) physically. Disconnect the tail light connector, disassemble the connector housing, remove the two pins using a paper clip, switch, insert, assemble the connector. Just make sure when the headlights are on, transmission gear "D" mode, no brake, then only the C shape lights(#2) is on and all of Brake 1(#4), Brake 3(#6), Brake 2(HGB)(#5) are off. At transmission gear "P" mode, #5(HGB, or Brake 2) will be on. If you switch pin #5 <-> #6 physically, #6 will be on.
You could be right. Fog light(#8) needs 10 cm (4 inch) clearance from the brake lights. So,
(After 2019) #5 should be turned off, not the #6
(Before 2019) #6 should be turned off
In the variant coding, there is an option; BC_R222(Rear SAM) / [096] OLC Bremslicht Schreiben (OLC Brake Light Settings) / PLSM_Deakt_BLbeiNSL (Turn off brake lights X when rear fog light is on). But the options are only "Brake 1", "Brake 2", "Brake 3", "Off". There is no option for HGB. Pin #5 is connected to not the Brake 2 but HGB. So I guess it's not possible to switch the two pins with the variant coding.
You may switch the two pins (#5 <-> #6) physically. Disconnect the tail light connector, disassemble the connector housing, remove the two pins using a paper clip, switch, insert, assemble the connector. Just make sure when the headlights are on, transmission gear "D" mode, no brake, then only the C shape lights(#2) is on and all of Brake 1(#4), Brake 3(#6), Brake 2(HGB)(#5) are off. At transmission gear "P" mode, #5(HGB, or Brake 2) will be on. If you switch pin #5 <-> #6 physically, #6 will be on.
No changes to light with transmission in gear. In variant coding, I only see options to change brake 1 or brake 3 light off with fog but none for pin 5 because its basically a running light when the headlights are on.
Update: Pin 5 powered the lower LED tube on the pre facelift tail lights. I believe the section below is the reason why pin 5 is working as a parking light 😀
Last edited by Stealthy17; 07-29-2022 at 02:52 PM.
10-28-2021, 06:57 PM
