LT-FLASH

Keeping LT1 PCMs alive, one flash at a time.

LT-FLASH Instructions & Getting Started

Welcome to the LT-FLASH support and instructions page. Here you’ll find basic setup information, operating guidelines, and helpful tips for using LT-FLASH hardware and software with supported GM LT1 Powertrain Control Modules (PCMs).

Please review the instructions for your specific product before connecting hardware or performing PCM read, write, or recovery operations.

LT-FLASHv2 – PCM Reading & Reflashing Hardware

LT-FLASHv2 is a USB-based PCM communication interface designed for reading, reflashing, and data logging on 1996–1997 GM LT1 OBD-II PCMs.

Basic Setup:

  1. Connect LT-FLASHv2 to your computer using the supplied USB cable.
  2. Connect the interface to the vehicle’s OBD-II diagnostic port using the supplied DB9-to-OBD-II cable, or connect through the OBD-BENCHBOX for bench operation.
  3. Turn the vehicle ignition ON without starting the engine when performing PCM read/write operations.
  4. Launch the LT-FLASHER software.
  5. Select the appropriate communication port and operation.

Important Information:

  • Always save a backup of the original PCM calibration before making modifications.
  • Maintain a stable power supply throughout the reflashing process.
  • Do not disconnect cables or interrupt power during PCM writing.
  • LT-FLASHv2 includes two 0–5V analog inputs for compatible external sensors, including wideband oxygen sensor controllers.

LT-UNBRICK – PCM Recovery Hardware

LT-UNBRICK is designed to recover supported 1994–1997 GM LT1 PCMs that have become unresponsive due to an interrupted or failed flashing operation.

Unlike normal reflashing, PCM recovery requires direct access to the PCM’s internal hardware.

Basic Requirements:

  1. Remove the PCM from the vehicle.
  2. Open the PCM housing to access the internal circuit board.
  3. Install the required recovery header according to the LT-UNBRICK installation instructions.
  4. Connect the LT-UNBRICK hardware and provide the required PCM power and ground connections.
  5. Launch the LT-UNBRICK software and follow the appropriate recovery procedure.

Powering the PCM:

The PCM can be powered using the OBD-BENCHBOX or the optional LT-UNBRICK PCM Wiring Harness with a suitable external 12V DC power supply.

The optional wiring harness provides an economical alternative to purchasing a complete bench setup when only PCM power connections are required.

Important: Verify all connections before applying power. Incorrect wiring or reverse polarity can permanently damage the PCM.

OBD BENCHBOX – Bench-Top PCM Power & Communication

The OBD-BENCHBOX provides a convenient solution for powering and communicating with supported PCMs outside the vehicle.

It eliminates the need to use a vehicle for many PCM reading, reflashing, and diagnostic operations.

Basic Setup:

  1. Ensure the bench power supply is turned OFF.
  2. Connect the appropriate PCM wiring connectors to the OBD-BENCHBOX.
  3. Connect LT-FLASHv2 to the OBD-BENCHBOX diagnostic port.
  4. Connect the required power supply.
  5. Apply power to the PCM and launch the appropriate LT-FLASH software.

Benefits:

  • Perform PCM operations outside the vehicle.
  • Convenient access to power and communication connections.
  • Reduce repeated installation and removal of PCMs during testing.
  • Ideal for bench-top reflashing, diagnostics, and development work.

Important: Always verify the PCM wiring configuration and required voltage before applying power.

LT-FLASH Software Instructions

LT-FLASHER – PCM Reading & Reflashing Software

LT-FLASHER is the Windows application used with LT-FLASH hardware to communicate with supported GM PCMs.

The software provides PCM reading and writing functions for calibration management and reflashing.

Basic Operation:

  1. Connect the LT-FLASH hardware to your computer and PCM.
  2. Launch LT-FLASHER.
  3. Select the correct communication port.
  4. Establish communication with the PCM.
  5. Choose the desired read or write operation.
  6. Follow the displayed instructions until the operation is complete.

Before Writing a PCM:

  • Verify that the calibration file is compatible with the target PCM.
  • Save the original PCM calibration whenever possible.
  • Ensure the vehicle battery or bench power supply is stable.
  • Close other applications that may be using the same communication port.
  • Never disconnect the interface during a write operation.

An interrupted flash can leave the PCM unresponsive and may require recovery using LT-UNBRICK.

LT-UNBRICK Software – PCM Recovery

The LT-UNBRICK Windows application works with LT-UNBRICK hardware to perform recovery operations on supported LT1 PCMs.

This software is intended for recovery situations where the PCM can no longer be accessed through normal flashing methods.

Getting Started:

  1. Install the required CH340/CH341 USB driver before connecting the recovery hardware.
  2. Connect the LT-UNBRICK hardware to the computer.
  3. Complete the required PCM recovery connections.
  4. Apply the appropriate external PCM power.
  5. Open the LT-UNBRICK application.
  6. Follow the software instructions for the recovery operation.

Important: LT-UNBRICK is not intended to replace LT-FLASHER for normal PCM reflashing. It is a dedicated recovery solution for supported PCM failures.

LT-LOGGER – Real-Time PCM Data Logging

LT-LOGGER provides real-time diagnostic data logging for supported GM LT1 PCMs using the LT-FLASH communication interface.

Logging allows users to monitor engine operating conditions, diagnose performance issues, and collect information for calibration adjustments.

Available Diagnostic Data May Include:

  • Engine RPM and vehicle speed
  • Engine coolant temperature
  • Manifold Absolute Pressure (MAP)
  • Mass Airflow (MAF)
  • Short-term and long-term fuel trims
  • Oxygen sensor activity
  • Ignition timing and knock-related information
  • Open-loop and closed-loop operating status
  • Wideband AFR data when a compatible external input is configured

Basic Logging Procedure:

  1. Connect LT-FLASHv2 to the vehicle.
  2. Launch LT-FLASHER and access the logging functions.
  3. Configure the desired parameters.
  4. Establish communication with the PCM.
  5. Start data recording.
  6. Stop logging when finished and save the recorded information.

Recorded data can be used for diagnostics and further analysis with compatible logging and analysis tools.

Important: Never operate a laptop or make software adjustments while driving. Have a passenger operate the logging software or perform testing in a safe, controlled environment.

General Safety & Best Practices

  • Always verify wiring and polarity before powering a PCM.
  • Use a stable, properly regulated power supply.
  • Never connect or disconnect PCM power wiring while energized.
  • Confirm that calibration files match the intended PCM and application.
  • Keep a backup of known-good calibration files.
  • Do not interrupt PCM read, write, or recovery operations.
  • Follow the installation instructions for any required USB drivers.
  • Use the appropriate LT-FLASH hardware and software for the intended operation.

Need Additional Help?

If you’re unsure which product or software application is required for your PCM, contact LT-FLASH support before proceeding.

When requesting assistance, please include your PCM year, hardware being used, software version, and a description of the issue. Screenshots of any error messages may also help identify the problem.