P0720
Fault code P0720Output shaft speed inductive pickup [Output Speed Sensor Circuit]
The PSM signal is used for further calculations.
NOTE: Stiff shifting operations with the vehicle standing. In the event of a double fault (output shaft speed inductive pickup and PSM fault), the reverse gear can be engaged during driving. The output shaft speed is then calculated via the input shaft speed.
NOTE: The ignition must be switched off and then switched on again in order to display a fault indication in the instrument cluster.
Diagnostic conditions
- Voltage greater than 10.2 V and less than 15.5 V
- Ignition on
- Internal Tiptronic control unit function test completed successfully
- Engine running without malfunction, speed '> 400 rpm'
- Brake not actuated
- PSM speed > 10 km/h
- CAN drive functioning
- No PSM faults
Measured input voltage less than 0.2 V or greater than 3.8 V for 100 msec. The fault is stored in fault memory after five occurrences.
Possible causes of fault
- 'Electrical fault in circuit', short circuit to B+ in wiring harness
- 'Electrical fault in circuit', short circuit within wiring harness
- 'Electrical fault in circuit', short circuit to ground in wiring harness
- 'Electrical fault in circuit', open circuit in wiring harness
- 'Electrical fault in circuit', Tiptronic control unit fault
Affected pins
Tiptronic control unit plug:
- Pin 38 'output shaft speed inductive pickup', to existing transmission wiring plug 'pin B5'
- Pin 50 'output shaft speed inductive pickup', to existing transmission wiring plug 'pin B6'
Diagnosis/troubleshooting G 0210
Wiring diagram for output shaft speed inductive pickup
1 - Tiptronic control unit
2a - Pulse wheel
2b - Inductive pickup
38 - Pin (38)
50 - Pin (50)
I - Current flow
Data on 'output shaft speed inductive pickup'
The internal resistance cannot be measured.
- Sensor Type: Hall IC
- Max. current: 65 mA
- No. of pulses: 24 per output shaft revolution
NOTE:
Visual inspection: In the next troubleshooting section, please check first that the affected 'pins' on the Tiptronic control unit plug connection and the 'pins' on the 'existing transmission wiring' plug connection are neither damaged nor corroded. Remove any soiling or corrosion/oxidation. Replace damaged parts/wires.
NOTE:
Control unit replacement: Before replacing the 'Tiptronic control unit', the ground connections, power supply and plug connections on the control unit must be checked as OK. Please observe the coding of the control unit. After the test drive, read out the fault memory again with the Porsche System Tester II No. 9588. Additional causes of faults that could damage the 'Tiptronic control unit' should be detected and remedied.
DANGER:
Danger of burns from hot ATF fluid.
Skin or clothing may burn following contact with hot ATF fluid.
- Always allow ATF fluid to cool before draining.
- Wear suitable protective clothing.
- Use a suitable collecting container.
