Tesla Model S/X Small Drive Unit ("SDU")

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Tesla uses the Small Drive Unit (SDU) in dual-motor versions of the Model S/X. The Front SDU (FDU) is found in performance and non-performance dual-motor models, while the Rear SDU (RDSU) is only found in non-performance dual motor models.


Small Drive Unit ("SDU") Data Connector

Low Voltage Data Connector

Small Front Drive Unit ("SDU") Data Schematic


Molex MX150 33472-2002 (key “B”)


22 AWG:      Molex 33012-2003

18-20 AWG: Molex 33012-2002

14-16 AWG: Molex 33012-2001

High Voltage Power Connectors

Although the connectors are known (Rosenberger HPK series), they are not available through conventional vendors.

Drop-in control board

Tesla SDU drop-in board

This board replaces the original board that comes with the OEM Tesla drive train. As opposed to the latter this board lets you use the drive train in the first place and allows you to fine-tune driving behaviour with the usual set of openinverter parameters. It does not restrict you in power output or regen input.

You can fully control the board via CAN or via a set of digital and analog inputs.


Wiring connections


Purchase in openinverter shop


Setup FAQ

MX150 male header receptacle STL on Thingiverse

Application Info

The board comes programmed with a recent software version. Please check github for recent software releases. In addition the board comes with a set of parameters appropriate to run the Tesla SDU. So it will work out of the box. Parameters that must not be changed are hidden to eliminate sources of error.

It is essential that the tripmode parameter is set to 1 "DcSwOn". Also do not use a low value fuse while testing. On over current trips some energy is still stored in the motor and it has nowhere to go if the contactor/fuse opens leading to immediate destruction of your inverter.

You will need to solder the supplied connectors and the current sensors embedded into the inverter assembly to the board, see this video.

To test run your drive unit, supply the board with 12V and GND on Conn6.13 and Conn6.19, respectively. Also supply 12V to Conn6.5 to select forward direction.

Supply inverter with some high voltage. For first tests it is recommended to put a large resistor/heating element/kettle in series.

You can start in manual mode using the button on the web interface and enter like 1Hz for „Fslipspnt“ and some value between 10-50 for „ampnom“ to see if the motor spins up. Be careful because manual mode does not enforce a motor speed limit!

You may also set parameter „udcsw“ and „udcmin“ to 0 and start drive mode by pulsing 12V on Conn6.9. Then connect a pot between Conn6.4, Conn6.7 and Conn6.8 (wiper). This will also spin the motor AND enforce a speed limit.


Small Front Drive Unit (FDU)

Tesla FDU cooling

Small Rear Drive Unit (SRDU)

Tesla SRDU cooling