Safety Functions

Safety Functions
Manually Engaged Downshifts
Manual downshifts are not carried out at excessively high speeds. At a vehicle speed above approx. 5 mph (8 km/h), the reverse lock (solenoid valve 3) prevents reverse gear being shifted hydraulically.

On-Board Diagnostics
By way of plausibility checks and checking the line connections for shorts or breaks, the control unit can detect and store defects.

Mechanical Emergency Program
In the event of failure of the transmission control or when defects are detected which lead to critical driving situations (e.g. impermissible down-shifts), the mechanical emergency program is activated, i.e. the transmission control unit is switched off and the failure display activated. A self-test of the entire safety hardware is performed during each new start.
Restricted driving of the vehicle is still possible in the emergency program (-> 4th gear). Various substitute programs are also made available depending on the type of defect which has occurred. For instance, in the case of solenoid valve I having a short to positive, only restricted gearshifts from 2nd to 4th gear are performed and the fault indicator is activated.