Hello Paul, my Mercedes ML 320 CDI 4MATIC has failed to start. The issue started as an intermittent fault after I left a washing bay a few days ago. There is a beeping sound and a message on the display: ‘Drive to workshop without changing gear.’ What does this mean? Muhwezi
Hello Disan, you might have a faulty automatic transmission ISM (Intelligent Servo Module). This control unit should ordinarily be able to recognize the stick shift position when you shift from parking to reverse or drive. When the ISM fails, it may act as though the gear stick shift is in reverse or drive instead of parking or neutral. This will prevent you from starting the car.
Often, it will activate the “drive to workshop without changing gear” warning message. Intermittently, it will prevent the car from starting as it assumes the shift stick is in gear not in parking. You will also not be able to shift from parking. A computer diagnosis will quickly confirm ISM failure.
Recovery of the vehicle may require a free wheeler tool or a diagnostic reset of the fault to be able to shift from parking.
It is best to have the ISM replaced by the local appointed Mercedes dealer in case online programming is needed. Common causes of failure are water intrusion into the control unit hence causing corrosion damage.