Mercedes-Benz S400 car ECO function can not be used

A driving distance of about 75,000 km, equipped with 276 twin-turbo engine Mercedes-Benz S400 sedan. Customer Response: The vehicle ECO function can't be used.mb sd connect compact 4
     Fault diagnosis: after the car to start the car, no alarm on the instrument, connect the  MB SD C5 diagnostic computer for rapid testing, the control unit are no fault code. And the customer road test to verify the fault phenomenon, found that the ECO indicator on the instrument has been yellow, driving for a long time will not turn green.5054A
     Using the diagnostic computer into the engine control unit (ME) in the ECO state actual value, found that the actual value is normal, as shown in Figure 1.Foxwell NT510 Scanner

As the actual value shows normal, can not determine the fault range, try to engine control unit, transmission control unit, ESP control unit, before the SAM and after the SAM control unit are upgraded, the fault remains the same. Then after the throttle cleaning and 10min power failure, the fault still did not improve.OBD2
    First look at the ECO start / stop function How it works: When the vehicle is at rest, the ECO start / stop function automatically turns off the engine and starts the engine as soon as the driver wants to start. Turning the engine off when the vehicle is stationary can reduce fuel consumption emission. The engine control unit continually performs system diagnostics and evaluates the system status of the ECO start / stop function. All systems involved in the ECO start / stop function continually check their status and send this status to the powertrain control unit (N127) and send them to the ME control unit via the CAN C1 (drive system area network). If the functional requirements are met, the "ECO" symbol in the dashboard is green to inform the driver that the ECO start / stop function is ready.Autel PS100
    The function sequence of the engine auto stop is: If the following functional requirements are met, the ME control unit will shut down the engine. ECO start / stop function button lights up (that the system is fault-free and ECO start / stop function enabled); speed is 0; coolant temperature between 60 ~ 115 ℃; transmission oil temperature between 10 ~ 120 ℃ ; The engine speed is within the specified range; the range is at "D" or "flash"; the accelerator pedal is not operating; the running brake has been actuated until the vehicle is stopped; the brake booster has sufficient vacuum; the air suspension system , The auxiliary brake system and the distance control system do not perform the operation intervention function; the hood is closed: no collision signal; the steering wheel angular velocity is within the specified value range; the vehicle electrical system is in normal condition; the driver's door is closed and the driver's seat belt The temperature inside the car has been adjusted.http://www.x431tool.com/