SXTune Documentation
Documentation / Programming firmware & calibration files

Getting Started

Programming firmware & calibration files

The established SXTune procedure for programming ECU firmware or calibration files, including CAN-interface recovery and the alternative PDM workflow.

Programming requires stable ECU power. Do not interrupt the ECU supply, switched ignition, CAN connection or USB connection while programming is in progress.

Before you start

  1. Ensure the ECU is powered with its normal 12 V supply, ground and switched ignition.
  2. Use the latest version of SXTune and make sure the correct ECU type / script folder is selected.
  3. Where possible, connect to the ECU first. A successful connection proves that the PC, CAN interface and ECU are communicating before programming begins.
ECU and script selection
Confirm the correct ECU / script selection before programming.
SXTune connected to ECU
A successful connection is preferable before programming because it confirms CAN communication.

Programming ECU firmware

  1. With the ECU powered and preferably connected, click Program ECU from file on the main toolbar.
  2. In the file chooser select Firmware Binary Files (*.bin), choose the firmware file supplied for the ECU and click Open.
  3. When SXTune instructs you to turn the switched 12 V ignition off, turn it off and then click OK.
  4. Turn the switched ignition back on when SXTune instructs you to do so.
  5. The firmware binary is then loaded into the ECU. Do not disturb ECU power, the USB lead or the CAN wiring during this stage.
  6. Wait for the programming-complete message. SXTune then restarts and reconnects to the ECU automatically.
Connection first is recommended, not essential. SXTune can program firmware without first connecting with the green Connect button. Connecting first is preferable because it confirms that the CAN interface is communicating correctly with the ECU.
SXTune main toolbar
Main toolbar. Use the Program ECU from file command to start ECU programming.
Choose firmware binary file
Firmware file chooser: select the correct ECU binary file.

Programming a calibration file into the ECU

The programming sequence is the same as for firmware, except that a calibration file is selected rather than a firmware binary.

  1. Power the ECU, confirm the correct ECU / scripts and preferably connect to the ECU.
  2. Click Program ECU from file.
  3. Select Calibration Files in the file-type selector, choose the required calibration file and click Open.
  4. Turn switched ignition off when instructed, then acknowledge the dialog.
  5. Turn switched ignition back on when instructed.
  6. Wait for programming to complete. SXTune then restarts and reconnects automatically.
Programming a calibration is different from opening one in SXTune. The normal Load Calibration command loads a file into the application for viewing/editing. Program ECU from file writes the selected calibration into the ECU.
Load calibration file
Normal calibration loading for editing is separate from programming a calibration into the ECU.
Save calibration file
Keep a known-good calibration file before making major changes or programming another calibration.

If programming fails

If a problem occurs while programming, repeat the procedure only after resetting the CAN interface. Disconnect the interface from both the PC USB connection and the D-SUB 9 / OBD connection so it fully powers down. Reconnect it and confirm that the ECU still has a reliable 12 V supply and switched ignition before trying again.

Recovering communication with the CAN interface

On rare occasions SXTune and the CAN interface can lose synchronisation because the interface is set to a bus speed that does not match the ECU, or the existing ECU firmware has been corrupted during an interrupted programming attempt. Use the following recovery procedure:

  1. Close SXTune. If it is unresponsive, close it using the Windows close-program dialog or Task Manager.
  2. Disconnect both the D-SUB 9 / OBD cable and the USB cable from the CAN interface.
  3. Wait at least two seconds, then reconnect only the USB cable. Leave the ECU-side cable disconnected.
  4. Start SXTune, but do not try to connect to the ECU.
  5. Open Config. In the CAN Interface section choose 1 Mbit/s and press Set.
  6. Reconnect the D-SUB 9 / OBD cable.
  7. Do not use the green Connect button. Click Program ECU from file and perform the normal programming procedure, including the requested ignition off/on cycle.
  8. If programming still cannot establish communication, repeat the procedure using 500 kbit/s and then 250 kbit/s.
Why this works: programming can be started without an ordinary SXTune-to-ECU connection, allowing the correct firmware to be restored even when the normal communication settings are wrong.

PDM installations: alternative calibration loading

Some power distribution modules can make the normal switched-ignition sequence difficult when loading calibration files. Use this alternative procedure:

  1. Connect to the ECU normally.
  2. Open ECU Configuration → ECU Configuration.
  3. Click Load Cal → RAM and select the calibration file to load.
  4. At the end of loading, a Windows-level programming failed SB message may appear with this method. This temporary message can be ignored.
  5. Click Save at the bottom of SXTune. This copies the calibration held in SXTune / ECU RAM into the ECU.
  6. Disconnect and reconnect to the ECU. SXTune reloads the calibration from the ECU; verify that the expected changes are present.