OBD1 GM: Getting Started


This is intended to provide a brief overview of the steps required to get up and running tuning an OBD1 GM vehicle.  It is deliberately vague.  Instead of providing an exhaustive guide here, there are a series of links to smaller tasks and explanations.  94-95 LT1 vehicles are going to be an exception not covered by this guide as they are tuned via reflash only.  See the 94-95 LT1 getting started page for more.  The “What do I need GM” section is going to have basic hardware and software suggestions for groups of vehicles.


  1. Install chip adapter.  The particulars of this will depend on which chip adapter you have exactly
  2. Plug in Moates devices to your PC.  With most modern operating systems, FTDI USB drivers should install automatically via Windows Update.  In the event things don’t go smoothly, look at the USB troubleshooting guide.
  3. Download and install tuning software.  TunerCat OBD1 Tuner And TunerPro RT are the usual candidates.  This guide will cover TunerPro RT
  4. Download XDF, ADX as appropriate for the vehicle you are working on.
  5. Read your stock chip using a BURN2 or APU1 to get your stock bin OR download one online that should work
  6. Load appropriate files in TunerPro:
    • XDF first: Select XDF (this is a map of the tables and parameters to edit in a bin)
    • ADX second: Acquisition… Load Definition (this is a guide of how to communicate with the vehicle and retrieve data)
    • BIN third: File… Open (this is the actual file that goes on the chip, in the ECM, running the vehicle)
  7. Configure TunerPro to log:
  8. Get the program you want in the ECM
    • Option A: Burn a chip with the BURN2 / APU1
    • Option B: Realtime tuning
      • With Ostrich2 you will need a SocketBooster for 24 pin applications!
      • 32 pin applications work best with Ostrich2
      • APU1 works for 24 and 28 pin applications with no additional adapters
      • After you have loaded a valid BIN file, disable checksum.  To do this, change the Mask ID from it’s “normal” value (i.e. $8D hex or $6E hex or $0D hex or $42 hex) to $AA (that is “AA” in hexadecimal).  This will allow you to make changes live without angering the computer.  CRITICAL.
      • After you have a checksum-disabled bin, press the blue “up arrow” to load your bin form TunerPro to hardware
      • If you want changes to happen as you make them in TunerPro, click the blue “chip” icon near the arrows to enable or disable emulation.  You should see the status in the lower left change to indicate emulation is active
  9. Start logging.  Click the two arrows pointing away from each other.  If TunerPro can connect, you should see the lower status bar change to say “DA: Connected” along with how fast it is receiving data packets in Hertz.
  10. Tune the vehicle.

Final Words

If you have prior tuning experience with other products, you may want to look at this article which discusses the differences between more modern tuning systems and TunerPro RT on OBD1 GM.

If you don’t have prior tuning experience, you are highly advised to do some serious reading on thirdgen.org’s DIY PROM board and gearhead-efi.com to get up to speed a bit.