Component Tests and General Diagnostics

Learning Function Of Electric Throttle Valve Actuator

It is necessary to adapt the engine control module and throttle valve in order to compensate for component tolerances. For this purpose, the emergency air setting (position of deactivated throttle valve) and the lower mechanical stop (throttle fully closed) are learnt independently in predefined test.

The return spring is also checked. Its task is to close the throttle valve in the event of fault.

Conditions

The following conditions must be fulfillled in order to be able to carry out the adaptation:
- Battery voltage > 10 V
- Engine speed < 32 RPM
- Vehicle speed < 2 km/h
- Intake air temperature > -10° C
- Engine temperature > -10° C, < 142° C

In addition, there must be no fault in the throttle potentiometer.

Adaptation Procedure

The position of the throttle valve with no power applied is checked every time the ignition is turned to position 2. The throttle valve must be set at the emergency air setting in this position. At the emergency air setting the spring force keeps the throttle valve open by a defined gap in order to maintain sufficient air for emergency engine operation when the valve is switched off. A fault code is entered if the measured emergency air setting is outside the permissible range.

By opening the throttle valve and then switching it off, it is possible to check whether the return spring can return the throttle valve to the emergency air setting. There is also a defined fault code for this setting.

The lower mechanical stop must also be learned in order to prevent the valve moving against it during operation. A fault code is also entered if the measured lower mechanical stop is outside the permissible range.

If the conditions for adaptation are not fulfillled but adaptation was already carried out once successfully the adaptation procedure will be simply terminated without a fault code being entered. The values of the adaptation previously performed will apply.

If the conditions for adaptation are not fulfillled and adaptation has not yet been carried out successfully (e.g. replacement of engine control module or throttle valve), the adaptation procedure will be terminated with corresponding fault code entry.

In all fault cases, only emergency operation of the engine is permitted as reliable operation of the throttle valve is not ensured.