Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › E350 Brake Spontaneously Locking Up › Reply To: E350 Brake Spontaneously Locking Up February 29, 2020 at 8:07 pm #940958 Richard KirshyParticipant You need to be looking at live data for all four speed sensors when the issue happens. That will at least tell if there is a faulty one.