Self-Study Program

54
Gearbox control unit
1)
The vehicle is normally driven away in first gear.
It can also be driven away in second gear by
shifting up into second before setting off
(with steering wheel tiptronic or selector lever).
This makes driving away easier on low friction
road surfaces, e.g. on icy or snow-covered roads.
2)
In addition to manual gearshifting, the tiptronic
function is, for example, necessary for making
use of the engine braking effect.
The selector lever gate (with positions "D" and "S")
does not allow intervention in order to prevent
upshifts or downshifts. The tiptronic function
(selector lever in tiptronic gate) can be used to
maintain the actual gear position or to select a
different gear within the shift limits. In this way,
as mentioned, it is possible to use the engine
braking effect and prevent repeated shifting back
and forth between gears (e.g. in trailer towing
mode).
tiptronic shift strategy
– Automatic upshift upon reaching maximum
engine speed
– Automatic downshift when engine speed drops
below the minimum threshold
– Kick-down
– Drive-away in second gear by selecting second
before setting off
1)
– Upshift prevention and downshift prevention
2)
Sport program "S"
In selector lever position "S", a performance-
oriented shift program is available to the driver.
When the gearbox control unit is informed that the
selector lever is in the "S" position, it alters the
gearbox shift characteristic so it is biased toward
higher engine speeds. This enhances driving
dynamics.
When the selector lever is n position "S",
DSP also adapts to driver inputs
(driver type analysis) and driving situations.
The "S" program also has the following special
features:
– If the selector lever is moved into the "S" position
under constant acceleration, the gearbox kicks
down within defined limits.
– To ensure a more direct driving response to
movement of the accelerator, the vehicle is,
where possible, operated with the converter
lockup clutch closed.
– If sixth gear is configured as an overdrive gear,
only gears 1 to 5 are selected.