abrdo

My brake lights are staying on all the time any suggestions on what it could be? according to dealer there is no brake light switch on the brake pedal.

SickSpeedMonte

I find that a bit hard to believe... try looking under there yourself. There has to be a switch somewhere for the lights, cruise control disable, BAS, etc.

On my older car, the brake light switch will sometimes come out of algnment with the pedal and keep the lights on.

Glyn M Ruck

This is an interesting one. My previous Benz had a pressure switch in the system -
(i.e. when pressure came up in the system under braking it turned on the lights) - nothing on the pedal. I suspect that the pressure switch is probably now integral with the ABS but it might still be separate. Sorry I can't answer this one definitively but tell the dealer to wake up - I'm pretty certain that there is a pressure switch somewhere.

BF_JC230

Yeah - This one made me laugh...the dealer says no switch on pedal...is that the extent of their knowledge...How do you trust some one to work on / fix your car if they don't know how the stop lamps turn on?

MMMMMMM...
Jake

Glyn M Ruck

OK - Some research & we have the answer - There might be some discrepency from market to market as to when this was instituted but this is the best data I can establish regarding US cars.

Brake Light Activation

Pre facelift

The brake light switch is on the pedal bracket up high above the brake pedal, there is a little offset to it but it strikes the pedal itself. 2 connectors on the US versions,

Post facelift

Electronic Stability System (ESP)
• Private-Bus (CAN)
– CAN between ESP and micromechanical turn rate sensor
(B25/15)
– 2-wire CAN used to transmit rotational speed and lateral
acceleration data to ESP

• Brake light control
– Brake switch eliminated
– Release contact of BAS system used to determine brake
application
(brake pressure & membrane travel used as back up)
– Redundant signals

• Discrete wired from ESPàSAM-D (looped)àSAM-R
• CAN signal ESPàEISàSAM-R
• SAM-R confirmation reply via CAN
– Brake light suppression via CAN message from ESP

This is extracted from a huge, DB pdf. file that I can no ways attach here. See highlighted under Brake Light Control

Please take this to your jerk dealer to assist him with fixing the problem - Good luck This is not a DIY

abrdo

thanks for your help, I have been under the dash all day and I really don't think there is a swith on the pedal, but I do feel that there is a pressure switch, although when I disconnect them (there are 2)the lights stay on, when I disconnected the ESP control the lights went out, is it possible that it is something else, since that part is 900 bucks!

Glyn M Ruck

You have a 2005 - it's not on the pedal. It's activated by the Brake Assist (BAS). Keep us informed. I'll try & do some homework on the brake assist. Must go to bed 4am in the morning this end

ghost87

Sorry for bumping this old thread but I have the same problem... :-(
Did somebody found a solution?

ghost87

I just call the dealer with the VIN and they said it is the Pedal Travel Sensor or the Brake Booster...so any ideas where is the problem?
Thanks in advance!!!

phister

sometimes its the contacts in the socket of the holder. if you remove your bulb and look at the contacts inside, sometimes theyve been know to overheat and fuse together causing a constant in the brake light or the light not working anymore. you can sometimes fix it by removing the melted parts, of course with the harness disconnected. if its too damaged you'll need a new one.

Benfica777

Very common on w204 aswell. May not be the issue here, however its been seen.

Moxostoma

I'm having this problem with my 2000 C230. The "Brake Pads Worn Down" light is on and all three brake lights stay on all the time. The two must be related, but how?