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This release is obsolete

Please use our latest release instead.

This release is obsolete


Please don't use this in your only car. This is new software, and you'll be among the first people in the world to use it. If something goes wrong, it may be a while before you drive that car again.

Make sure that any changes you apply to a PCM are compatible with the operating system that is currently on that PCM. In a future release, the app will try to prevent you from flashing incompatible changes, however in this release you need to ensure compatibility yourself.

This release of the PCM Hammer utility will allow you to read and write the contents of a General Motors '411 Powertrain Control Module (PCM). While the read feature will read the entire contents of the PCM, the write feature is currently limited to the calibration and parameter sections.

(We want to make sure that calibration and parameter writes are working flawlessly before we try rewriting the operating system, because if the calibration or parameter section are defective, the PCM is relatively easy to return to working order. But if the operating system isn't perfect, that's a bigger problem.)

To use this release, unzip all of the files into an empty directory, and run PcmHammer.exe. When the window appears, the first thing you'll need to do is select the device that you're using. Then click Read Properties to confirm that you've selected the device correctly - it should print a few details about your PCM. Then try "Read Contents."

If you're feeling bold... and if you have a different car that you can use to drive to work... try writing the calibration or parameter blocks.

Note that reading will work with both P01 (512kb) and P59 (1mb) PCMs, but writing will only work with a P01 PCM. We expect to add support for P59 PCMs soon.

This is our first public release, so you will be among the first people to test it. You may encounter bugs. The software may behave in strange ways. Please report such things to us so that we can fix them.

If anything goes wrong, please take detailed notes about the exact steps that you took, and please also copy the contents of the Debug tab and save it to a file. We'll need that to figure out what went wrong, how to fix it, and how to prevent it from happening to anyone else.

The developers can be reached by creating a new thread at

While we think it is impossible for this software to make your car unusable, please keep in mind that we're just a bunch of hobbyists who have been working on this stuff in our spare time. It's a miracle that we've gotten this far. If you need the guarantees that come with a commercial product, you should buy a commercial product.