Upshifting in curves is not prevented

Detectable faults: Open circuit/short to ground, short to positive

1) Check voltage at transverse acceleration sensor pin 3 with the ignition switched on.

2) Pull connector off Tiptonic control unit. Igniton "Off".

Check wiring from Tiptronic control unit connector pin 45 to pin 27 and to transverse acceleration sensor pin 3 for continuity, short to ground and short to positive.

Fault, fault code Possible causes, elimination, remarks

Test point 5 Tiptronic warning lamp comes on, transmission is in emergency mode.

Rpm signal <- DME Detectable faults: Open circuit/short to ground, short to positive,

Fault code 21 loose connection

1) Signal check

Check signal with Tester 9288. (Engine operation)

Check signal with oscilloscope at Tiptronic control unit connector pin. If signal is o.k.: Tiptronic control unit faulty

Signal shape

2) Open circuit, short to ground, short to positive

Check wiring connections from DME control unit pin 6 to Tiptronic control unit pin 3, diagnosis socket pin 14 and combi-instrument connector B pin 3.

Wiring connections o.k.: DME control unit faulty Note:

If pin 3 of the DME control unit is shorted to ground, the DME relay cannot drop out and the fuel pump will run on even when the engine is switched off. This is also the case if a short to ground is found in the wirings to the Tipronic control unit.

Fault, fault code Possible causes, elimination, remarks

Test point 6 Tiptronic warning lamp comes on, transmission is in emergency mode.

Load signal DME Detectable faults: Open circuit/short to ground, short to positive,

Fault code 22 loose connection

1) Signal check

- Check signal with Tester 9288 (injection time) with the engine running

- Check signal with oscilloscope at Tiptronic control unit connector pin 21.

If signal is o.k.: Tiptronic control unit faulty Signal shape of ti-signal

2) Open circuit, short to ground, short to positive

Check wiring. Tiptronic control unit connector pin 21 to DME connector pin 17 (ground at Tiptronic control unit connector pin 7, positive at Tiptronic control unit connector pin 1)

Fault, fault code Possible causes, elimination, remarks

Test point 7 Tiptronic warning lamp comes on, transmission is in emergency mode.

Change of ignition timing Detectable faults: Open circuit/short to ground, short to positive Fault code 24 ^ Check operation with Tester 9288 (drive link test).

- Idle speed drops during test. If not:

- Check coding plug at DME.

2) Check voltage drop

- Remove cover from plugged-in connector T46.

- Switch on ignition

- Measure voltage at pin 6. Nominal value approx. 5 volts

- Trigger signal with Tester. Voltage must drop.

- Display o.k.: Check wiring to DME control unit (T 46 pin 6 to DME control unit pin 51).

- Wiring o.k.: DME control unit faulty

- Display not o.k.: Check wiring to Tiptronic control unit (T 46 pin 6 to Tiptronic control unit pin 32).

- Wiring o.k.: Tiptronic control unit faulty Figs. 1,2

Note: Check engine-to-body ground strap!

Fault, fault code

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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