Reading And Writing Values
Information
Transfer gear with gas nitrocarburised (GNC) "hardened" steel plates.
- Check compatibility of hardware (transfer gear) and software.
- If a transfer gear with GNC plates is installed for the first time, the PR number LU2 must be written under Maintenance of vehicle data in the PIWIS Tester.
Information
- If the transfer gear with servo motor (control unit) is replaced, there is no need to reload data (classification data).
- This data is already contained in the control unit for servo motor and transmission bundle replacement.
- If only the servo motor (control unit) is replaced, the data (wear values, classification data, etc.) must be read out of the old control unit and written into the new one using the PIWIS Tester.
- If the data can no longer be read out, the classification data on the transfer gear housing must be read off and written using the PIWIS Tester: - > All-wheel\Maintenance/repairs\Control unit replacement
- Classification data can be found on the transfer gear housing.
Only valid for model year 2011 - 2012:
> 391300 All-wheel drive control unit needs to be replaced: Missing offset and gradient values on the transfer gear (66/11)
Example: classification data for transfer gear
Information
If only the all-wheel drive electronics (PTM) control unit is replaced, select the "Control unit replacement" function.
If the All-wheel drive electronics (PTM) control unit and transfer box are replaced, the "Control units and transmission replacement (together)" function must be selected.
Voltage drop
- Risk of irreparable damage to control unit
- Risk of damage to control unit
- Fault entries in the control unit
- Coding in the control unit is aborted
- Malfunctions in control unit, even during programming
→ 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 90 A to the vehicle battery.
Information
The PIWIS Tester 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 on the PIWIS Tester.
- PIWIS Tester must be connected to the vehicle before starting it. Switch on ignition and press F12 to continue.
- Select the required control unit All-wheel drive in the overview.
- Select the Control unit replacement procedure in the Maintenance/repairs menu.
- Select Read out data from old control unit.
- Replace the all-wheel drive control unit on the vehicle.
- Select the Write data to new control unit/Start-up
function.
- 6.1 A start-up is only possible with the correct control unit. During the procedure, it is also checked whether a VTG with GNC steel plates is installed in the vehicle. For this purpose, the part number must be read off the transfer gear.
- 6.2 Within the function, it is checked whether the correct control unit with suitable software has been ordered and installed.
- 6.3 If necessary, the PR number LU2 (LU2 = GNC plates) is automatically written.
- Read out and erase fault memory.
- Perform a test drive.