Throttle Control Actuator: Description and Operation

Traction Control System (TCS) throttle Body, Description Of Function
- The TCS throttle body is mounted beside the ordinary throttle body and consists of body, butterfly, electric motor and link arm. In the TCS OFF mode, the current is cut and the throttle is opened by a spring.

Important
- The TCS throttle must not be adjusted.

Feed To Butterfly Actuator Motor
- The TCS butterfly actuator motor is fed voltage by a 500 Hz Pulse Width Modulation (PWM) outlet from pins 18 and 35 on the control module. The motor can be driven in both directions by changing the poles.
- When the butterfly is closed, the voltage across pins 18 and 35 is approximately 3.5 Volts.
- In the case of mechanical or electrical faults in the actuator motor or position sensor, or in the connecting leads, diagnostic trouble codes are registered by the system. The TCS OFF lamp lights and the system is disengaged.
- As a spare part, the TCS throttle body is changed as one unit.
- The TCS system is self-calibrating, see under "Control Module".





Throttle Disc Potentiometer
- Information from the TCS butterfly position sensor is received by the control module on pin 27.
- Depending on the position of the TCS butterfly, the voltage varies between approx. 1.2 - 4.4 Volts.
- The position sensor is fed with 5 volts from pin 3 on the control module and is grounded via control module pin 20.





Main Butterfly Position Signal, Description Of Function
- To synchronize the TCS butterfly in relation to the main butterfly, the TCS control module receives a position signal on pin 11 from pin 54 on the MOTRONIC control module. The signal, which is 100 Hz PWM, gives the position of the main butterfly and measures approx 1.2 Volts at idling.
- In the case of a spurious throttle position signal or an interruption/short in the circuit, diagnostic trouble codes are registered by the system, the TCS OFF lamp lights and the system is disengaged.
- When the ignition is switched into the drive position and when the starter motor is running, the MOTRONIC control module sends an engine temperature signal instead of a throttle position signal to pin 11 on the TCS control module.
- When the engine is switched off and the ignition is in the drive position, the signal measures approx. 0.25-1.0 Volts, depending on the engine temperature.
- If the engine temperature signal is wrong, diagnostic trouble codes will be registered in the MOTRONIC system. In this case, no diagnostic trouble code is registered in the TCS system.
- See also "Disconnection, full-load enrichment system ".