Electronic Throttle Control Module: Description and Operation

DME And EML Diagram:

The electronic throttle control (EML) system replaces the mechanical system of engine speed regulation by way of throttle valve and accelerator pedal connected by a cable.

EML Control Unit Location:

The EML system control unit which is located in the E-Box electrically controls the engine speed according to various programs by regulating the throttle position motors. The EML system also controls automatic synchronization of both DME systems, idle speed control, cruise control function, and progressive throttle opening curves which can change to suit specific driving conditions.


EML inputs included:

^ Motronic Control Unit 1 (DME) provides an injection and engine speed signal. The injection signal is monitored by the EML control unit and compared to engine speed for plausibility.
^ Motronic Control Unit 2 (DME) provides an injection signal for cylinders 7-12.
^ Water temperature sensor.
^ Air conditioning relay.
^ Compressor clutch.
^ Cruise control switch.
^ Instrument cluster for the vehicle speed signal.
^ Brake light switch.
^ Automatic transmission program switch.

These input signals are used by the EML control unit to regulate the engine speed for all driving modes.
The EML system is equipped with a self-diagnostic system. Faults that occur with the system are recognized by the control unit and stored in the memory. Certain faults will also cause the EML warning lamp to illuminate on the instrument cluster. Furthermore, the EML system incorporates an emergency running program for failure of certain components and signals which will allow the vehicle to be driven to a dealership or other qualified repair facility. Diagnosis and troubleshooting of the EML system may only be carried out with the BMW diagnostic module (service tester).