Bench Flashing a GM PCM




Introduction: Bench Flashing a GM PCM

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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    2 years ago

    It's been a while I see the post time, lol. Very interested in this for a side project. Can you email me more info? pic at pickydesignz dot com


    7 years ago on Introduction

    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