Reading And Writing Values

→ Prior to disconnecting the control unit, switch off ignition and remove ignition key.

→ Ensure that the power supply is not interrupted during programming.

→ Connect a battery charger with a current rating of at least → Nominal value: 40 A  to the vehicle battery.

Information 

The PIWIS Tester II 9818  instructions take precedence since the description may be different with later Tester releases.

The procedure described here has been structured in general terms. Different text or additional information may appear in PIWIS Tester II 9818  .

1. Connect the PIWIS Tester to the vehicle and start the Tester. Switch on ignition and press [F12] to continue.
2. Select the vehicle type and start the diagnostic application.
3. Select the All-wheel  control unit in the overview  .
4. Select Maintenance/repairs  .
5. Select Control unit replacement  and press [F12].

   Information 

   Only select the function if just the control unit will be replaced. If the control unit and transfer gear will be replaced, "Control unit and transmission replacement (together)" must be selected.

6. Read out data from the installed control unit  and press [F12].
7. Select Read control unit data  and press [F12].
8. The Tester displays the message Control unit data read-out successful  . Press [F12] to continue.
9. Switch off ignition and replace control unit. → WM 391355 REPLACING TRANSFER GEAR CONTROL UNIT 
10. Switch on ignition. Select Write data to new control unit/Start-up  in the menu (procedure described above) and press [F12].
11. Enter the chassis number and press [F12] to continue.
12. Select Write data  and press [F8] to start. The data that was read out is now loaded.
13. The Tester displays the message Data was written successfully to the control unit  . Press [F12].
14. Switch off ignition and press [F12]
15. Start the engine and press [F12]
16. Read out the fault memory and erase it if necessary.