Electronic Throttle Control (EDR) S62 Engine

The electronic throttle control system (EDR) was developed specifically for the S62 engine. The design criteria was to develop an EML system capable of actuating the eight throttles while ensuring that the power potential of the S62 engine was not compromised. The three main components of the system include the pedal position sensor (PWG), EDR motor, and MS S52 engine control system which is responsible for operation and monitoring of the throttle control system. The pedal position sensor is the driver's input for increased torque output of the engine. The PWG input is processed by the MS S52 control module. Plausibility checks are carried out and the EDR motor is operated to open the throttle valves. All eight throttle valves are opened simultaneously through the linkages connected to the EDR. The system requires approximately 120 ms to fully open the closed throttle valves. Feedback of the current throttle valve position is achieved through 2 throttle valve potentiometers located on the ends of the throttle valve shafts.

PWG provides 2 separate variable voltage signals to the MS S52 control module for determining the request for EDR operation. The MS S52 monitors the changing signal ranges of both circuits as the pedal is pressed from idle to full throttle. PWG Pot No. 1. is 0.5-4.5 volts. PWG Pot No. 2 is 0.5-2.0 volts. PWG pot signal No. 1 is the primary input for throttle opening request. The signal from Pot No. 2. is used primarily for plausibility checking. If the signal ranges are incorrect, MS S52 will activate an emergency operating program based on the specific fault recognized.

As a safety check, a pre-drive check of the EDR system is carried out every time the ignition is switched on. MS S52 control module briefly opens the throttles and checks zero set point of the feedback potentiometers, free movement of the throttle valves, operation of the EDR actuator motor, and operation of the return springs in the EDR actuator motor.

There are a total of 4 emergency operation programs stored in the MS S52 control module. The MS S52 control module will activate one of these programs depending on which fault is present or what component failed. With any fault that is relevant to the EDR system, the engine's output torque will be reduced to provide limited driveability of the vehicle.

Emergency program No. 1 is engine operation with PWG input. The engine's output torque is limited to 480 Nm. This program will set with faults in one PWG sensor input or one throttle valve feedback input.

Emergency program No. 2 is engine operation through the idle valve actuator. The engine's output torque is limited to 300 Nm and the vehicle's speed to 70 MPH. With program No. 2, the throttle valves are shut down and only the idle valve is used for engine operation. This program will set with a fault in one air mass sensor input and one PWG sensor input.

Emergency program No. 3 is engine operation with jammed throttle valves. The engine's output torque is limited to 300 Nm and the speed is limited to 35 MPH. This is carried out through ignition and injection intervention if the MS S52 senses that the throttle valves are jammed or stuck and cannot be closed by applying power through the EDR actuator.

Emergency program No. 4 is engine operation with a control module internal fault. The engine's output torque is limited to 250 NM and the speed is limited to 35 MPH. Depending on the degree of the fault, the control module with the dual processors will enable limited engine operation.