Electronic Throttle

Electric Throttle







the Electric Throttle control valve is controlled by the APP sensor via the ECM. the throttle valve plate is positioned by gear reduction DC motor drive. the DC motor is controlled by a proportionally switched high/low PWM signals at a basic frequency of 2000Hz. Engine idle speed control is a function of the Electric Throttle control valve therefore a separate idle control valve is not required.

the electric throttle control valve throttle plate position is monitored by two integrated potentiometers. the potentiometers provide DC voltage feedback signals to the ECM for throttle and idle control functions.

Potentiometer one is used as a the primary signal potentiometer two is used as a plausibility check through the total range of throttle plate movement.

If the ECM detects a plausibility error between Pot 1 and Pot 2 it will calculate the inducted air mass from the air mass (from the air mass sensor) and only utilize the potentiometer signal which closely matches the detected intake air mass. It does this to provide a fail-safe operation by using a virtual potentiometer as a comparative source.

If the ECM cannot calculate a plausible value from the monitored potentiometers (1 and 2) the throttle motor is switched off and the fuel injection cut out is activated.

the electric throttle control valve is continuously monitored during operation. It is also briefly activated when the ignition switch is initially turned to position II. This is done to check the valves mechanical integrity by monitoring the motor control amperage and the reaction speed of the feedback potentiometers.

Should the electronic throttle need replacing the adaption values of the previous unit will need to be cleared from the ECM. This is achieved by the following process:
1. Using TestBook/T4 clear the adaption values.
2. Switch the igniting "OFF" for 10 seconds.
3. Switch the ignition "ON" for approximately 30 seconds the electric throttle control valve is briefly activated allowing the ECM to learn the new component.

This procedure is also necessary after the ECM has been replaced. However the adaption values do not require clearing since they have not yet been established.