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 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 valve body control or when defects are detected which lead to critical driving situations (e.g.: impermissible downshifts), the mechanical emergency program is activated. Power supply to the solenoid valves in the transmission control unit is switched "Off" (emergency program) and the failure display activated. The vehicle can only be driven with restrictions in the mechanical emergency program, i.e. only the 3rd, 4th gears and reverse can be shifted. In this case, 3rd gear is engaged in the selector lever position "2" and "1", 4th gear in position "D" and "3" and reverse in position "R". The main pressure assumes its maximum value and the reverse lock and P/N shift-lock, if installed, of the selector lever are not active.

CAUTION: A downshift from 4th to 3rd can be triggered by pulling back the selector lever to position "2" or "1".

EGS Control System Failure
In the event of failure of the control unit, the power supply to the solenoid valves is cut (emergency program).