brake lights won't shut off 2011 e350 convertible
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 19
Likes: 4
2011 E350 cabriolet
brake lights won't shut off 2011 e350 convertible
HELLO
I am having an issue with my brake lights. They are on all the time when the car is running. The brake switch is new, just installed.
If i ground out pin 4 wire, the brake lights work as normal, but the ECS and traction lights come on.
If its normal the brake lights come on when I start the car, no brake lights if car if off, no warning lights on the dash, cruise control does not work, I can shift out of park if I step on the brake.
My Icarsoft V3 says the S9 ( brake pedal switch ) is active when I am not pressing the brake pedal.
This could be a wiring issue.
I used the car for a year with pin 4 grounded. Brake lights worked as normal, but I had error lights ESC and traction and cruise did not work.
I'd like to get this fixed but don't know where to start.
The brake pedal switch is new and it should be self adjusting when installed,
The brake pads are 75%
I have not looked at the brake fluid level,
Any advice on where to start looking?
( I tried to upload the schematic for the S9 brake switch but this system wouldn't let me , has 4 wires going to switch )
thanks for any input
Kip
I am having an issue with my brake lights. They are on all the time when the car is running. The brake switch is new, just installed.
If i ground out pin 4 wire, the brake lights work as normal, but the ECS and traction lights come on.
If its normal the brake lights come on when I start the car, no brake lights if car if off, no warning lights on the dash, cruise control does not work, I can shift out of park if I step on the brake.
My Icarsoft V3 says the S9 ( brake pedal switch ) is active when I am not pressing the brake pedal.
This could be a wiring issue.
I used the car for a year with pin 4 grounded. Brake lights worked as normal, but I had error lights ESC and traction and cruise did not work.
I'd like to get this fixed but don't know where to start.
The brake pedal switch is new and it should be self adjusting when installed,
The brake pads are 75%
I have not looked at the brake fluid level,
Any advice on where to start looking?
( I tried to upload the schematic for the S9 brake switch but this system wouldn't let me , has 4 wires going to switch )
thanks for any input
Kip
Out Of Control!!
Joined: Apr 2019
Posts: 11,957
Likes: 6,796
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
This is really odd.
The new switch should have fixed it.
What else is going on... how did that happened?
Once you get your schematic you can use a voltmeter to track activation.
The new switch should have fixed it.
What else is going on... how did that happened?
Once you get your schematic you can use a voltmeter to track activation.
Last edited by CaliBenzDriver; Nov 10, 2025 at 10:36 PM.
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 19
Likes: 4
2011 E350 cabriolet
Its an odd switch. Not mechanical, there are 4 wires : 1) is 12 volts, 2) is ground 3 & 4 connect to the can bus. I think I know the problem, I think the ground is bad.
Somehow its suppose to be 2 switches in one. I'll find out tomorrow if the ground is good
Kip
Somehow its suppose to be 2 switches in one. I'll find out tomorrow if the ground is good
Kip
Out Of Control!!
Joined: Apr 2019
Posts: 11,957
Likes: 6,796
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Mercedes E-class are built with painted GND posts.
- Peel back driver side footwell carpet
- DISCONNECT BOTH electric batteries
- disconnect each of the footwell GND circuits
- clean each one better than new.
- I believe 5x count in total
- Reconnect batteries
Guess what now... passenger side footwell is awaiting for another day.
MBWorld Fanatic!
Joined: May 2018
Posts: 6,607
Likes: 6,554
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
HELLO
I am having an issue with my brake lights. They are on all the time when the car is running. The brake switch is new, just installed.
If i ground out pin 4 wire, the brake lights work as normal, but the ECS and traction lights come on.
If its normal the brake lights come on when I start the car, no brake lights if car if off, no warning lights on the dash, cruise control does not work, I can shift out of park if I step on the brake.
My Icarsoft V3 says the S9 ( brake pedal switch ) is active when I am not pressing the brake pedal.
This could be a wiring issue.
I used the car for a year with pin 4 grounded. Brake lights worked as normal, but I had error lights ESC and traction and cruise did not work.
I'd like to get this fixed but don't know where to start.
The brake pedal switch is new and it should be self adjusting when installed,
The brake pads are 75%
I have not looked at the brake fluid level,
Any advice on where to start looking?
( I tried to upload the schematic for the S9 brake switch but this system wouldn't let me , has 4 wires going to switch )
thanks for any input
Kip
I am having an issue with my brake lights. They are on all the time when the car is running. The brake switch is new, just installed.
If i ground out pin 4 wire, the brake lights work as normal, but the ECS and traction lights come on.
If its normal the brake lights come on when I start the car, no brake lights if car if off, no warning lights on the dash, cruise control does not work, I can shift out of park if I step on the brake.
My Icarsoft V3 says the S9 ( brake pedal switch ) is active when I am not pressing the brake pedal.
This could be a wiring issue.
I used the car for a year with pin 4 grounded. Brake lights worked as normal, but I had error lights ESC and traction and cruise did not work.
I'd like to get this fixed but don't know where to start.
The brake pedal switch is new and it should be self adjusting when installed,
The brake pads are 75%
I have not looked at the brake fluid level,
Any advice on where to start looking?
( I tried to upload the schematic for the S9 brake switch but this system wouldn't let me , has 4 wires going to switch )
thanks for any input
Kip
Start at post #6
https://mbworld.org/forums/e-class-w...ml#post8630013
.
Good luck....
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 19
Likes: 4
2011 E350 cabriolet
Problem solved.
The switch had no ground. I connected a ground wire to the brown wire and everything is working, even the cruise control. Thank for the help. I do want to point out that the color code of my wires were completely off from the schematic that I found. A Black wire was suppose to be in pin 1 ( and 12 volts ) and it was in pin 3. It was very hard to tell if the pin 2 wire was indeed brown and suppose to be the ground. I ended up having to rely on a pic from another post to pick which one was suppose to be the ground. It worked. I got lucky. None of my wiring was the colors they should have been.
Thanks again for the help.
I have no trouble lights on my dash
Yippie !!!!!
kip 2011 E350 convertible
The switch had no ground. I connected a ground wire to the brown wire and everything is working, even the cruise control. Thank for the help. I do want to point out that the color code of my wires were completely off from the schematic that I found. A Black wire was suppose to be in pin 1 ( and 12 volts ) and it was in pin 3. It was very hard to tell if the pin 2 wire was indeed brown and suppose to be the ground. I ended up having to rely on a pic from another post to pick which one was suppose to be the ground. It worked. I got lucky. None of my wiring was the colors they should have been.
Thanks again for the help.
I have no trouble lights on my dash
Yippie !!!!!
kip 2011 E350 convertible
Out Of Control!!
Joined: Apr 2019
Posts: 11,957
Likes: 6,796
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
long term fix...
Problem solved.
The switch had no ground. I connected a ground wire to the brown wire and everything is working, even the cruise control. Thank for the help. I do want to point out that the color code of my wires were completely off from the schematic that I found. A Black wire was suppose to be in pin 1 ( and 12 volts ) and it was in pin 3. It was very hard to tell if the pin 2 wire was indeed brown and suppose to be the ground. I ended up having to rely on a pic from another post to pick which one was suppose to be the ground. It worked. I got lucky. None of my wiring was the colors they should have been.
Thanks again for the help.
I have no trouble lights on my dash
Yippie !!!!!
kip 2011 E350 convertible
The switch had no ground. I connected a ground wire to the brown wire and everything is working, even the cruise control. Thank for the help. I do want to point out that the color code of my wires were completely off from the schematic that I found. A Black wire was suppose to be in pin 1 ( and 12 volts ) and it was in pin 3. It was very hard to tell if the pin 2 wire was indeed brown and suppose to be the ground. I ended up having to rely on a pic from another post to pick which one was suppose to be the ground. It worked. I got lucky. None of my wiring was the colors they should have been.
Thanks again for the help.
I have no trouble lights on my dash
Yippie !!!!!
kip 2011 E350 convertible
you may now be back feeding GND through undersized wiring.
Now that you know what is wrong, fix the marginal GND source without bypass. Trace the circuit with diagram (regardless of mismatched colord).
By the time you reach footwell, you'll get rewarded with a handful of poor GND posts.
Last edited by CaliBenzDriver; Nov 12, 2025 at 10:52 PM.
