Hi, your next step is to have the traction control system scanned for fault codes. If the warning lights are consistently coming on at that speed I suspect that you have a fault code stored for the wheel speed sensors. You should also check all of your tires and make sure they are all the correct size.
Let me know if you have any questions.
Tires are all the same size.
Can you recommend an ABS scanner for the Mercedes, there are so many on line and I want to but one the works with the car. Or how do I check the wheel sensor with a multimeter. I had a CV boot go bad and I think that the grease may have damaged the right front sensor.
On the scan tool I use the Mercedes Star Diagnosis system and am not familiar with anything else that is out there. The problem with checking the sensor with an ohmmeter is that the problem occurs at 60 mph. You probably won't detect a fault with the meter.
You can ohm out the sensor and move the sensor harness around and see if the reading drops out on you. Also make sure you do not have any loose wheel bearings.