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Replaced the brake switch to resolve an issue where with the ignition on the brake lights will stay on all the time + ESP/ABS lights. Unfortunately, new switch didn’t solve the problem. I’ve noticed that with the switch disconnected the brake lights are working just fine.
I used a Mercedes scan tool and it came up with "430A00 The signal of component S9/1 (Brake light switch) is unreasonable" ( with/without the switch)
Does anyone have the WIS electrical diagram for the brake circuit so that I can troubleshoot the other components in the circuit? Vehicle is a 2011 E350 cdi blue efficiency.
Bad switch or the tip of the switch needs to be adjusted. Push on the brake pedal and adjust the switch by pushing in.
on w212 the switch is different , no tip to adjust.
press the pedal all the way down , push the switch in , depress the pedal and it will adjust the switch.
Live data shows two signals of the component and second one is all the time actuated (with the switch connected/ disconnected or the pedal pressed/depressed) that’s why now I think to check the wiring
Fuse 21 of Front SAM feed power to S9/1 Stop Lamp Switch.
By symbol this switch is not a pure mechanical one, it has electronic inside.
S9/1 is wired-to and is under Adaptive Brake wiring diaghram, Module N30/4.
High Suspect short to ground on the Red-White pin 4 of switch or White wire pin3 of switch, brown wire pin 2 of switch is not likely shorted, but you best check too.
Fuse 21 of Front SAM feed power to S9/1 Stop Lamp Switch.
By symbol this switch is not a pure mechanical one, it has electronic inside.
S9/1 is wired-to and is under Adaptive Brake wiring diaghram, Module N30/4.
High Suspect short to ground on the Red-White pin 4 of switch or White wire pin3 of switch, brown wire pin 2 of switch is not likely shorted, but you best check too.
Happy troubleshoooting
Exactly what I was looking for, thanks a lot.
I can see now :
pin1 (black) - 12v power supply
pin2 (brown) - ground
pin3 (yellow in my case) - high signal
pin4 (red/white) - low signal
that’s what I thought and I replaced it whit an original Mercedes switch and even ordered one on eBay and I’m getting same problem.
The brake pedal module drives the F-SAM module. Third sensor replaced with no improvement, then what
DTC 430A00: The signal of component S9/1 (Brake light switch) is unreasonable" ( with/without the switch)
Crazy SAMs are not perceived as terribly robust! They must run NON-STOP 24/7 so I call them sleepless... unlike other modules that are power managed, by the work of SAM's. Given enough glitching, SAM's start seriously impacting processings of other CAN Module they are connected to.
> Have you tried a quick battery REBOOT yet?
Additionally some fault conditions require a software reset to resume normal functions.
Last edited by CaliBenzDriver; Sep 7, 2022 at 03:03 PM.
I think the S9/1 switch being electronic is to allow the Front SAM to test its state of health.
If it is a common normally open switch, the SAM probably can't send its comprehensive type diagnostic signal
Also the dual channel it has, could be that it uses opposite switching strategy thingy as safety.
Say brake pedal NOT pressed, channel 1 CLOSED and channel 2 OPEN.
When brake pedal pressed, channel 1 becomes OPEN and channel 2 becomes CLOSED.
The accelerator pedal and throttle body also uses the same safety concept, 2 channels opposing each other in operation, something like that.
I think the S9/1 switch being electronic is to allow the Front SAM to test its state of health.
If it is a common normally open switch, the SAM probably can't send its comprehensive type diagnostic signal
Also the dual channel it has, could be that it uses opposite switching strategy thingy as safety.
Say brake pedal NOT pressed, channel 1 CLOSED and channel 2 OPEN.
When brake pedal pressed, channel 1 becomes OPEN and channel 2 becomes CLOSED.
The accelerator pedal and throttle body also uses the same safety concept, 2 channels opposing each other in operation, something like that.
couldn’t wait for weekend so here I am near that footwell again, to find that I have no ground at all to the BLSW
With a ground from footwell light (temporarily) everything works again as it should
all the lights on the dash (abs,esp,…) gone as well
Now is all about finding that short on the brown cable ( pin2). I know there is a connector under the driver side carpet. So I’m suspecting a bad contact there as it looks well insulated
And Yes, you was right saying that it uses opposite switching .
On the first test I checked voltage on all four pins of the switch and I was getting 12v in pin1(12v power supply) and 12v in pin4(channel 2).
That’s why MB scanner shows with the brake pedal NOT pressed “signal number 2 actuated” and “signal number 1 NOT actuated”. With the pedal pressed “ signal number 1 actuated “ and “ signal number 2 NOT actuated “
Good job identifying poor GND as root cause of this failure.
Now pull driver side carpet and clean your painted GND posts... I think you'll find 2 or 3 in there towards front left and perhaps one is populated on the right side according to options package.
This will fix much more than just your break lights, your iCluster, F-SAM and associated modules will work more reliably with reduced glitches
Next step.... repeat on passenger side carpet, front seats, trunk, engine bay,....
contactless sensor core: snapped or glued??
Last edited by CaliBenzDriver; Sep 8, 2022 at 07:02 PM.
Agree with Cali, while solving this S9/1 ground, check all other grounds on driver footwell too.
I am beginning to see weird "habit" of Mercedes when it comes to choosing supplier for their wires.
The supposedly WHITE wire of pin 3 on photo is kind of yellow with spots/patches of white. The nice true white is shown on the RED/WHITE cable of pin 4.
Some wire jacket colors are really bad, misleading I would say. I found a few already this "bad".
Imagine if we can only access the middle part of the wire ( part of a big bundle ) and not its both ends, we could troubleshoot till 30th Febuary and can't find the correct wire
eobol , 08-01-2022 06:53 AM
Newbie
Does anybody have any experience with a brake light kill switch on the 212 facelift? I’ve got a ‘15 wagon and I’m very interested Quote Multi
#2
AngryScotsman , 08-01-2022 10:35 AM
Member
I had to google this to figure out what this is... and it is exactly what it sounds like, someone wanting to disable their brake lights -- for reasons.
Sounds extremely dumb, reckless, and a fun way to be sued to oblivion.
Good luck. Quote Multi 1
#3 EckFe1's Avatar EckFe1 , 08-06-2022 02:00 AM
Member
Very common usage in the US. Very helpful when speeding in a pack of cars. Radar from behind and the officer looks for brake lights.
Just find the switch at the brake pedal and extend/add wires and switch to your desired location. Quote Multi
#4
Baltistyle , 08-06-2022 06:43 AM
Senior Member
As someone that like to drive fast, this is quite possibly the stupidest and most dangerous “mod” I’ve ever seen. Take your tickets like an adult or learn how to drive better. Just about the dumbest comment would be to want to turn the brakes lights off in a pack of cars that are possibly speeding. It’s probably best to jump off the cliff now and save others the heartache of you killing there loved ones.
sued? Op Will be lucky if not killed by the accident he WILL cause.
AngryScotsman , 08-08-2022 10:04 AM
Member
ugh, street racers... they are a good argument for late term abortions. Quote Multi
#6 FastWgn's Avatar FastWgn , 08-08-2022 03:54 PM
Super Member
Quote:
Originally Posted by EckFe1 Very common usage in the US. Very helpful when speeding in a pack of cars. Radar from behind and the officer looks for brake lights.
Just find the switch at the brake pedal and extend/add wires and switch to your desired location.
Sure happy I live in an area where radar / laser from behind is rarely (if ever) used. The "oh ****" moment when they guy in front of you steps on his brakes for the random false alarm would scare the living daylights out of me....
tinmanwpk , 08-11-2022 10:45 AM
Junior Member
Quote:
Originally Posted by FastWgn Sure happy I live in an area where radar / laser from behind is rarely (if ever) used. The "oh ****" moment when they guy in front of you steps on his brakes for the random false alarm would scare the living daylights out of me....
Especially at speed. I had this "mod" when I was 16. I used it to ditch the cops where I lived. Never had it again. Quote Multi
#8
Sebko , Today 06:29 PM
Newbie Got a similar one here Heeeellllllpppppppp
Changed the switch and the fault is still there.
also i get an error from circuit 50 rear sam and when i look at the actuations i get variable voltages when I press the brake pedal.
Right when i start the car the voltage is around 10v which i believe it sends the error and if i restart straight after the voltage goes up and the esp light goes away from the dash.
Also it was working without fuse 21 in the slot as I recently bought the ******* only to figure out that the fuse was not even there?????
Im completely lost and dont know where to start.
Help!!!!
[QUOTE=S-Prihadi;8630013]Fuse 21 of Front SAM feed power to S9/1 Stop Lamp Switch.
By symbol this switch is not a pure mechanical one, it has electronic inside.
S9/1 is wired-to and is under Adaptive Brake wiring diaghram, Module N30/4.
High Suspect short to ground on the Red-White pin 4 of switch or White wire pin3 of switch, brown wire pin 2 of switch is not likely shorted, but you best check too.
I have voltage on the third wire from the switch but it voltmeter shows that is connected to ground.
Could it go thru the light bulbs or most likely to be ashort ?
I have chased the wire next to the driver seat but in rhe boot there is no pink /white as my third cable.
Tryed to measure backwards from the boot but there sre so many connected to the ground that Im losing hope.
The black wire (no2) its not a ground as it uses to transmit signal ? When i grounded the wire the esp / beake light switch came back.
I have an issue with my brake light switch wiring as well, My colors are different from yours. I have a 2011 W221 S65. I need help identifying Pin 1- 4. I have gotten a replacement pigtail, but I’m stuck on how to arrange the pins. Any help is highly appreciated.
Apologies, not giving more context. I didn’t do this, I found it that way. The car had ESP, ABS lights on, scanned it and i got a brake light switch error. I checked the switch and found the wires all clipped off and no connection to the switch. I already found a replacement connector, but can’t figure out the pin arrrangement.
oohhh, unlucky you.
Give me the car VIN, let me see what I can find to help you.
Also you have so many MB cars, you need to get ebay knock-off WIS-EPC version say 2020 or 2021.
We can't do any wiring check with confidence or mistake-less without those documents assist.
Even then MB wiring color sometimes is different on the car vs WIS
Last edited by S-Prihadi; Feb 22, 2025 at 01:40 AM.
Find attached PDF, I think it is for ur W221.1 S65 AMG.
I can say a 100% it is correct wiring diag, because no VIN data but one thing good S65 AMG is not common or comes with many variations like say S550.
Pin 1 - BLUE with GREY stripe ---> corrected 2:27PM my time. Damn my eyes !!! Its white stripe for my eyes.
Pin 2 - BLUE with Black stripe
Pin 3 - BLUE with green stripe
Pin 4 - BLUE with Orange stripe
I told you, MB sometimes is this bad for wire colors accuracy
I swear I am seeing ur 4 wires wire as GREEN.... and not BLUE, how about you ?
I am not color blind, but photo is sometimes OFF from auto white balance of camera
Last edited by S-Prihadi; Feb 22, 2025 at 02:33 AM.
Find attached PDF, I think it is for ur W221.1 S65 AMG.
I can say a 100% it is correct wiring diag, because no VIN data but one thing good S65 AMG is not common or comes with many variations like say S550.
Pin 1 - BLUE with GREY stripe ---> corrected 2:27PM my time. Damn my eyes !!! Its white stripe for my eyes.
Pin 2 - BLUE with Black stripe
Pin 3 - BLUE with green stripe
Pin 4 - BLUE with Orange stripe
I told you, MB sometimes is this bad for wire colors accuracy
I swear I am seeing ur 4 wires wire as GREEN.... and not BLUE, how about you ?
I am not color blind, but photo is sometimes OFF from auto white balance of camera
Originally Posted by S-Prihadi
Our PC monitor or tablet or smartphone screen color re-production may differ too.
I am using PC
Does below section of the wire in red circle look more towards blue too for you ?
-------------------
High possibility is that the physical wire BLUE- with Grey stripe is +12V , test it.. Corrected 2:30pm
Good luck
Originally Posted by S-Prihadi
oohhh, unlucky you.
Give me the car VIN, let me see what I can find to help you.
Also you have so many MB cars, you need to get ebay knock-off WIS-EPC version say 2020 or 2021.
We can't do any wiring check with confidence or mistake-less without those documents assist.
Even then MB wiring color sometimes is different on the car vs WIS
Thanks a LOT! This worked actually, Wired it in and the errors are gone!!! I’m so grateful. I’ll get WIS setup ASAP. I’m still left bewildered as to what could have happened initially. I’m going to take the car out for a spin, see how everything goes, but I’ll definitely keep an eye on things.
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) everything works again as it should
