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VGS-NAG3 9G-Tronic: TCU replacement using FBS4 data saved from the original unit

Mercedes Interface New Keys / Immo Medium ⏱ 1-2 hours 15 steps

Replacing a 9G-Tronic VGS-NAG3 transmission control unit while the original is still fitted and readable: read it on the car over OBDII, take the donor to virgin on the bench and personalise it with the original's data.

Required licences

  • MN034

Hardware / cables

  • AVDI
  • CB100/CB106 OBDII
  • ZN151 DS Box
  • CB403 DS-BOX Extended Cable Set
⚠ WarningThe virgin procedure on the donor is a bench job with ZN151 DS Box and CB403. Always save the configuration data as well as the FBS4 data: without it the personalisation is not complete. The unit activates automatically after 100 ignition cycles.

Procedure

  1. Connect the AVDI to the car's OBDII port with the original TCU still fitted.
  2. Open the Mercedes FBS4 Manager software and select "TCU".
  3. Press "Info" to establish the connection.
  4. Press "Save" to read and save the FBS4 data from the original unit.
  5. Back up the configuration: TCU > "Utilities" > "Save All Config Data".
  6. Set the donor unit up on the bench: connect the CB403 to the TCU connector as per the diagram, connect the AVDI to the ZN151 DS Box with the CB403 cable, connect the CB403 to the ZN151 DS Box and power the ZN151.
  7. Open the Mercedes FBS4 Manager software and select "TCU".
  8. Press "Info" to establish the connection with the donor.
  9. Take the unit to "Virgin" state with the dedicated button. From this point on (or if the unit is already virgin) you can carry on in the car over OBDII with an internal CAN connection.
  10. Press "Personalize" and select the file with the FBS4 data saved from the original TCU.
  11. When prompted, cycle the key IGN OFF and then ON to finalise the procedure.
  12. Program the configuration data with "Utilities" > "Program All Config Data" using the files saved from the original.
  13. Set the VIN of the car.
  14. If the software versions need matching up, press "Program".
  15. Tell the customer that automatic activation happens after 100 ignition cycles.

Reference screenshots

VGS-NAG3 9G-Tronic: TCU replacement using FBS4 data saved from the original unit — 1VGS-NAG3 9G-Tronic: TCU replacement using FBS4 data saved from the original unit — 2
Source: Manuale Mercedes FBS4 Manager, parte 2 di 2, cap. 5.2.1 e 5.2 connessioni (p.51, 53) · ⏱ estimated time 1-2 hours
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