BDM test Fixture for P01 and P59 Powertrain Control Modules, as used in a variety of GM cars and trucks in the late 1990s to early-mid 2000s.

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If you're working on software to fine-tune engines in these cars, you risk permanently damaging the PCM. There's a good chance that you can unbrick it using a debugging device. Traditionally, users would solder directly to the circuit board's solder pads, but this approach was inspired by David Braley's innovative method, which you can find here: https://pcmhacking.net/forums/viewtopic.php?f=42&t=6215&sid=4de2e1f85d6ee0f6bac79f82dafcbed4 He built his test fixture jig with a mill. I only have an FDM printer, so he sent me a drawing with all the key dimensions, and I transformed it into something printable. Fortunately, my new Prusa I3 MK3S is just small enough to fit this project. You'll need to add test pins, also known as "pogo pins," to mount in the fixture. I used these https://smile.amazon.com/gp/product/B07HC5VKVT/ but any similar product will do. If the outside diameter of the pin is not 0.9mm, you should adjust the hole size in the OpenScad file accordingly. You'll also need a USB-BDM-NT device from https://www.usbjtag.com/zenshop/index.php to reprogram your PCM. Solder it up, and you should be able to fine-tune your engine's performance. If you read the source code of the OpenScad file, you'll see how to print small test fixtures for trial-and-error experiments to find the right diameter for the pin holes. You want them to fit snugly so they stay in place under load but not so loosely that they move away from the circuit board and lose contact. Personally, I printed two test parts to get the diameter just right. Not shown here: you'll have to solder this up to the USB-BDM device and then hook it up to your computer. This method has been proven with both P01 (512kb) and P59 (1mb) PCMs.