Bench Flashing a GM PCM

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Introduction: Bench Flashing a GM PCM

About: Disclaimer: The author is not responsible for loss of life, limb or property. The author is not responsible for your actions. The author is not responsible for anything. In fact, the author is completely i...

Sometimes you just cant get to the car to reflash the ECM. Maybe you want to run a tuning business by mail or your like me and just looking to put something where it just doesn't belong. Like swapping a new fuel injected motor into and old hot rod.

I saw efilive had a nice PDF about bench wiring your PCM. I made a little adapter board just for GM PWM PCM's. This way I can flash a tune and leave the outside work for later....

Step 1: Just the Basics

I added an ALDL connector and a toggle switch for the ignition. In addition to power and ground I only wired pin 2 for the serial data since I only work on older GM stuff. You can add more pins if you want like CAN or GMLAN etc.

I added an alternate PCM connector. Its a 5 pin header that connects to a short cable with RS232 pins on the opposite end. The old RS232 pins fit pretty well onto the GM PCM pins. just cover them with a little shrink tubing and your done.

Step 2: Testing the Interface

Before I trust it to my expensive interface I'll test it out using elmscan and a $12 ELM327 box. If I get a good initialization I'll connect the hp interface next. Then flash a new tune and get it ready to be installed....

Step 3: Other Modules

You can do a similar thing for the other modules from your car. I use the same RS232 pins for the IPC and SIR modules.

The IPC is pretty simple and I just use a small protoboard to get +12V, Ground and Class 2 data to it.....

One of these may end up in my golf cart......

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    You mean a ls2 doesn't belong in a 1987 s10 blazer 4x4. Dang I wish somebody woulda told me 2 years ago.

    Nice write up