Vehicle: 2010 Mercedes Benz E 550 4MATIC Sedan,
5.5L V-8, Automatic Transmission
Problem: The shifter goes into “Park” while
driving under 12 miles per hour. There were no DTCs.
Details: The tech found that, while
monitoring the check park request PID from the TCM, a park
request was being received when the problem occurred. This meant
that the park assist module was requesting the transmission to
shift into park. The module that sends that signal to the park
assist module was the radar sensor control (RSC) module.
The tech unplugged the RSC module to see if that fixed the
problem. It did, so he checked the module for corrosion or water
intrusion. It checked out good.
Next, he tested all the electrical circuits and found that, when
the problem occurred, reference voltage from the RSC module to
the radar sensors dropped from 8 volts to 2 volts. He unplugged
the radar sensor and found the two middle sensors were shorting
the reference voltage from the RSC module.
Confirmed Repair: He replaced the two
center radar sensors and the problem was fixed!