This is how the information is processed in the Tiptronic control unit

Measured variables

Level o throttle valve engine r.p.m.

t speed

lateral acceleration

longitudinal acceleration

Adaption of shift characteristics (transmission and torque converter)

• summation ot data

• weighting shift characteristics TC characteristics!—

Manually selected gear shift

p

1 * shift up kit

J _ shift down

computer controlled maintenance of recommended max. engine speeds

772

The Tiptronic control unit is located in the luggage compartment, on the right side. The following parameters are constantly supplied to the Tiptronic control unit:

Parameter

• Throttle position

• Throttle actuation speed

• Driving speed

• Vehicle transverse acceleration

• Vehicle axial acceleration/deceleration

Type of measurement

Potentiometer resistance

Time for change of resistance at potentiometer

Frequency measurement (from DME)

No. of pulses at pole wheel of transmission shaft

Signal from transverse acceleration sensor below the right-hand seat

Change of no. of pulses within clock time

The above values are determined several times per second and are processed in the control unit.

By comparing those measurements with the stored programs, factors are generated that cause the transmission to enter or to shift into one of the five shift curves.

The automatic shift strategy of the Porsche Tiptronic

1428-37/38

1

ABS control unit

8

Selector lever system with two gates

2

ABS sensors at wheels

9

Cable

3

Speedometer

10

Position switch

4

Kickdown switch

11

Automatic transmission

5

DME control unit

12

Throttle with potentiometer

6

Tiptronic control unit

13

Engine

7

Transverse acceleration sensor

The Tiptronic control unit (6) is the information and command center of the entire system. A large quantity of information inputs that are compared with the stored driving or gearshift programs is used to generate commands that cause the transmission to execute or not to execute gearshifts.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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