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Reading and Flashing Your Ecu

(redirected from Documentation.ReadingAndWritingToEcu)

Q How exactly do I download and flash my rom image?

To read and flash a rom, your Subaru needs to be placed in diagnostics mode. To flash, you must also use a jumper block for the 01–05 WRX. A description of the process is found here:

Once you are in diagnostics mode, connect your OpenPort cable to your OBD-II port and your computer. Then open Ecuflash and select “read from ecu” from the ecu menu. Do not turn on your ignition until prompted to do so. When the box pops up, turn your ignition on, immediately hit OK and the bar at the bottom of the window will indicate the progress of the download. Once complete, choose the “save rom as” option from the File menu and choose a name for your rom (can be anything you want). Make sure, though, that the extension for your file is .hex or .bin (for example, my_stock_rom.hex ).

To flash (write), make sure you have installed the flash block connector (if applicable) and select the “Open rom” item from the file menu. Select the rom you wish to flash to your ecu and once it’s opened, select the “write to ecu” option from the ecu menu. You may also “test write to ecu” which doesn’t actually flash the changes, but tests the process to make sure the flashing sequence works properly. Another option is “Compare to ecu” which will compare the currently opened rom with the rom on the ecu. The progress of the flash will be shown at the bottom of the window. Any errors that occur will be listed in the right pane.

Here’s another guide to using Ecuflash:

Troubleshooting - Cannot flash or read your ECU:

  • Try a different port in the “Options” menu of Ecuflash.
  • Do not turn on your ignition until prompted to do so, otherwise reading/flashing may fail.
  • Make sure the openport cable is securely connected to both your car and the laptop.
  • Make sure you car is actually entering diagnostics mode. With the green diagnostics connectors connected and the openport cable disconnected, you should get a flashing CEL and the radiator fans should cycle on and off (after a period of time) when the ignition is turned on. If not, your car may have an additional connection near the passengerís side footwell that is disconnected. When reading and flashing, the radiator fans will remain off.
  • Make sure your battery, charging and electrical system are up to snuff.
  • When reading a rom, make sure you are selecting the correct year and model range for your car or the download will fail.
  • “Unknown ROM image” error - You may receive this message after downloading is complete. Ecuflash, like RomRaider, allows you to edit roms and has its own ecu definitions. When you are finished reading your rom, Ecuflash attempts to open it for editing but if it does not have a definition for your rom you will receive this error message. Choose the selection “Inherited from the definition below” and then from the drop-down box, choose the model and year that most closely matches your own. Then choose the “Save rom as” option from the file menu. Note: In this case, since you are essentially using another rom’s definition for your own image, there may be an issue when you decide to flash the image back to your ecu. This is because the flash method used for the rom you selected may not be correct for your vehicle possibly causing an unusable ecu when you go to flash. If you are in doubt, ask before you flash at the openecu forums: . Your selection to inherit, however, does not change the actual image downloaded from your ecu, so even if you get it wrong, the actual ecu image file will not be affected. This issue does not impact RomRaider’s ability to open and edit your rom.

This article is part of the official RomRaider FAQ.


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Page last modified on January 13, 2007, at 11:50 AM
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