Paul A. Romsky Jr. - Fiero GT ALDL Monitor
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* WARNING *
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Never operate a vehicle while using the Fiero GT ALDL Monitor or Adapters
(Tool) without an assistant. The driver must always have full
attention on driving, therefore, an assistant that is not driving is
required to operate the Tool in order to prevent loss of driving safety.
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* NOTICE *
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The author of the Fiero GT ALDL Monitor and Adapters (Tool) assumes no
liability for its use. The users assume all liability for any damages or
injury resulting from the use of this Tool.
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* NOTICE *
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The GUI will run only on a PC with Microsoft Windows 7 and up operating systems.
This is NOT an Android Application nor will it run on Apple operating systems.
The GUI will work on Windows XP but the drivers for the Adapter will not as XP is
no longer supported by Microsoft or by Adafruit.
The Fiero GT ALDL Monitor Adapter and GUI work only with:
Supported GM Pontiac Fiero V6 2.8L MPFI 1985 ECM 1226869 160 Baud ALDL
Supported GM Pontiac Fiero V6 2.8L MPFI 1986-1988 ECM 1227170 160 Baud ALDL
Next to Support GM Pontiac Fiero L4 2.5L TBI 1984 ECM 1226156 160 Baud ALDL
Supported GM Pontiac Fiero L4 2.5L TBI 1985-1986 ECM 1226864 160 Baud ALDL
Not Yet Supported GM Pontiac Fiero L4 2.5L TBI 1987-1988 ECM 1227748 8192 Baud ALDL
As of 1 May 2025, I started to revamp the GUI to support all Fiero ECMs. This is in the early stages and will require me to get a hold of each ECM so that I can validate the code. Contact me via E-mail for status on this effort.
The following links are screen shots of the Assembly Line Diagnostic Link (ALDL) Diagnostic Tool developed for Fieros. Pontiac Fieros were built before On-Board Diagnostics I (OBD-I) and On-Board Diagnostics II (OBD-II) were standardized. General Motor's (GM's) predecessor to OBD was the ALDL which simply outputs a constant stream of parameters so that the vehicle's Electronic Control Module (ECM) could be used to test and monitor the engine performance. Today, it is very difficult to find ALDL scanners on the open market, and the fact that GM was never forth coming on how ALDL worked only exasperated the problem. Fortunately, I have found various web sites that describe how the ALDL protocol works, so I decided to try my hand at interpreting these unique data streams. The Fiero ALDL Monitor GUI is the first result of that effort.
Note: These screens shots are not always up to date with the actual GUI, but they are close to the current revision.
Note: The Fiero ALDL Monitor GUI will work without the Adapter, but only playback files previously recorded and/or captured can be performed. When an Adapter is connected, Monitor, Record, and Capture can be performed as well. The GUI can also be used standalone without an Adapter to look-up Error Code (EC) definitions.
Fiero GT ALDL Monitor showing Playback Parameters and Playback Mode Panel
Fiero GT ALDL Diagnostic Tool - GUI Lamp Test
Fiero GT ALDL Diagnostic Tool - About
Fiero GT ALDL Diagnostic Tool - Adapter Check
Fiero GT ALDL Diagnostic Tool - Help
Fiero GT ALDL Diagnostic Tool - Setup
Fiero GT ALDL Diagnostic Tool - TPS Set Limits Utility
Fiero GT ALDL Diagnostic Tool - Mark Recording With Comment
Fiero GT ALDL Diagnostic Tool - Playback Modes
Fiero GT ALDL Diagnostic Tool - Playback
Fiero GT ALDL Diagnostic Tool - Mark And Comment Displayed Playback
Fiero GT ALDL Diagnostic Tool - Graph
Fiero GT ALDL Diagnostic Tool - Trace Identify
Fiero GT ALDL Diagnostic Tool - Performance Curves
Fiero GT ALDL Diagnostic Tool - Air/Fuel Blocks
Fiero GT ALDL Diagnostic Tool - O2/Voltage/AFR/Lambda Graph
Fiero GT ALDL Diagnostic Tool - Status Flags
Fiero GT ALDL Diagnostic Tool - Status Flag Info
Fiero GT ALDL Diagnostic Tool - Malfunction Flags
Fiero GT ALDL Diagnostic Tool - Malfunction Flag Info
Fiero GT ALDL Diagnostic Tool - Knocks Blocks
Fiero GT ALDL Diagnostic Tool - SES Error Codes
Fiero GT ALDL Diagnostic Tool - SES O2 Sensor
Fiero GT ALDL Diagnostic Tool - Error Code Info
Fiero GT ALDL Diagnostic Tool - Feature Selection
Fiero GT ALDL Diagnostic Tool - Reference Slides
Fiero GT ALDL Diagnostic Tool - VIN Lookup Utility
Fiero GT ALDL Diagnostic Tool - Recording Validation Utility
Video (14:16 minutes:seconds): Fiero GT ALDL Monitor and Adapter GUI Demonstration
Video (11:04 minutes:seconds): Fiero GT ALDL Monitor and Adapter In-Car Demonstration
Video (9:21 minutes:seconds): Zanrith using the Fiero GT ALDL Monitor and Adapter Driving Demonstration
The Special Introductory Offer has Sold Out
These are no longer available through this web page. They now being sold on E-Bay:
E-Bay Ad
Note: If the above link takes you to a sold out page, try:
1. Refreshing this page and trying the link again. -Or-
2. Go into E-Bay and search for "Fiero ALDL Monitor Tool Suite"
This is a photo of the latest version of the Fiero GT ALDL Adapter as of 30 AUG 2025.
Based on the Adafruit Trinket M0 Microcontroller
The Fiero ALDL Monitor software is free. It currently does not support the Serial ALDL Cables that are popular, the special High Performance Adapter (based on the Adafruit Trinket M0) must be used - contact me via E-mail for details.
Paul Romsky may be reached via E-mail at romsk22@gmail.com
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* NOTICE *
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If you are using V1.6.50 to V1.6.54, you need to update to V1.6.55 or later as soon as possible.
I had left some debug code in those releases that was forcing the Vehicle Speed to read 0 (for playback and recordings). V1.6.55 has removed that debug code.
Remember to save a copy of your Fiero_ALDL_Monitor.cfg file before installing the update so you can set your defaults back to your own settings.
If you are using V2.0.5 to V2.0.6, you need to update to V2.0.7 or later as soon as possible.
There was a bug preventing the Graph Parameters loading from the 1226869 ECM DLL.
The Power curves are now shown for L4 Engines.
The Tachometer now shows the proper Red Line for the L4 Engines.
V2.0.7 has fixed the bug and added the new features.
Remember to save a copy of your Fiero_ALDL_Monitor.cfg file before installing the update so you can set your defaults back to your own settings.
Download the Fiero ALDL Monitor GUI V2.0.7
Version 2.0.7 Dated 15 October 2025 8:44 AM EDT - Latest GUI Code.
Version 2.0.7 and up supports the High Performance ALDL Adapter based on the:
Adafruit Trinket M0 Microcontroller
This version includes the 'ALDL Toggle Mode' to help Test IAC Valves.
Download and Installation Instructions:
