1 other thing you could check is the 44 pin connector on the ABS right in front of the brake master cyl. If the connect or was ever off and not put back on properly it can cause the esp/bas light due to the pins not getting proper voltage. Also spray it down with WD40 if you see any condensation.

 

Maybe a code has been set and the problem stored, get the codes read.

 

I did and it isn't throwing any codes. I guess I need to check the plug in front of the master cylinder.

 

If it's an automatic it could be a brake light switch. I've had to change mine twice for this reason. When you take of the switch you can see the connector kind of has "burned spots" on it. The first one was pretty bad and the second switch only started to have a little bit. The Mercedes version lasted a lot longer than the Mopar version in my experience.

 

I have a new brake light switch so that was not it and calibrated it several times, replaced battery, checked the plug by the master cylinder. I guess it could be a speed wheel sensor. I don't know what else it could be. I have read of others with the same issue and that have done the same things as well as wheel speed sensors and still have the light. I don't have the spoiler going up and down either just the BAS/ESP light

 

Then it is either a yaw sensor or wheel sensor Only dealership or someone with right tools can read those codes. Good luck hope it is just a wheel sensor.

 

Thanks. I am debating weather to buy some wheel sensors and try that or clean them or just ignore it.

 

Did you use an original Mercedes brake light switch? It can make a difference in my experience. They are like less than $40.

 

The previous owner actually replaced it so I don't know. He seemed very into the car so I assume he used the correct switch. He was the one who directed me to this forum. I don't know his handle.

 

After reading this post, I was prompted to order me on of those new fangled cheap Chinese hand held oscilloscopes.
( $69 with shipping ).
I was a CE with NCR for 40 years and always had a Tektronix handy, not so much anymore as I am now in database support.
Anyway, in cases like this it will be handy.
Also handy for measuring CPS output, injector duty cycle, camshaft position sensor etc......