Limp Home Mode

Limp-home Mode
The functions stored for the limp-home mode in the Tiptronic control unit are divided into two categories: Limp-home mode 1 and limp-home mode 2.

The following table shows the shift response of the transmission in limp-home mode:

Limp-home mode 1

Fault not caused by incorrect gear ratio or unusual shifting.
Explanation of table headings and content:
- Shift state before setting fault: States the selected position of the selector lever and the selected gear before the fault occurs and is set.
- Step 1: After a fault occurs and is set, the Tiptronic control unit switches to limp-home mode and initiates the appropriate shift operation.
- Step 2: The vehicle is in motion and the shift operation initiated in Step 1 terminates.
- Step 3: Motion is interrupted and the vehicle stops. The Tiptronic control unit initiates the shift operation for gear 3 (the run will be continued in gear 3).
- Step 4: The shift operation initiated in Step 3 terminates and gear 3 is engaged.

Limp-home Mode 1 - Part 1:

Limp-home Mode 1 - Part 2:

Explanatory notes on content of table for Limp-home mode 1:

Power switch (in Tiptronic control unit):
With the power switch (in Tiptronic control unit) ON, the Tiptronic control unit can control the transmission.

With the power switch (in Tiptronic control unit) OFF, the Tiptronic control unit cannot control the transmission.

- D: Selector lever position gears 1, 2, 3, 4, 5, 6
- R: Selector lever position reverse gear
- B1 Shift solenoid valve B1 (modulation pressure)

Where the state given in the table is shown with a * or **, then the state is modified as follows:
- *: Gear 5 is engaged if a fault is present in the shift solenoid valve C1 (modulation pressure) (disengagement fault of the torque converter lockup clutch).
- **: Shifting is not possible if a fault is present in the shift solenoid valve C2 (modulation pressure) (engagement fault of the torque converter lockup clutch). If the selector lever is moved from D to N and back again to D, then the Tiptronic control unit shifts to gear 5. Differences: If the vehicle speed = 0 km/h and the period of 10 seconds set in the selector lever positions P, R, N expires, then gear 3 is engaged after changing the selector lever position from D to N and back again to D. If the selector lever is moved from D to N and back again to D in step 1 and step 2, the Tiptronic control unit shifts to gear 5.

In the event of a solenoid valve modulation pressure (main) fault, the torque is limited as follows:
- Selector lever in position D 150 Nm
- Selector lever in position R 100 Nm

Limp-home mode 2

Fault caused by incorrect gear ratio or unusual shifting.
Explanation of table headings and content:
- Shift state before setting fault: States the selected position of the selector lever and the selected gear before the fault occurs and is set.
- Step 1: Vehicle in motion. After a fault occurs and is set, the Tiptronic control unit switches to limp-home mode. The gear engaged before the fault was set remains and the torque converter lockup clutch is not activated.
- Step 2: Motion interrupted, the vehicles is stationary, the gear engaged in step 1 is held. Shift solenoid valve C2 (modulation pressure) and shift solenoid valve B1 (modulation pressure) are ON. All other shift solenoid valves are OFF. Shift operation for gear 3 is prepared.
- Step 3: Shift operation for gear 3 terminates and the gear is held. Neutral-detect is started.
- Step 4: Shift operation for gear 5 is initiated. No neutral state.
- Step 5: Shift operation for gear 5 terminates. No neutral state and the shift solenoid valves are disabled.

Limp-home Mode 2 - Part 1:

Limp-home Mode 2 - Part 2:

Power switch (in Tiptronic control unit):
With the power switch (in Tiptronic control unit) ON, the Tiptronic control unit can control the transmission.

With the power switch (in Tiptronic control unit) OFF, the Tiptronic control unit cannot control the transmission.