theogre

I got the AutoXray GM ECM scanner a couple days ago. It’s a nice unit. Small, easy to use, and as accurate as the ECM will allow it to be. Where’s what I’ve learned using it, and reading some other sites about the design of the ECM itself. The unit can be found for around 150$us. (there is a universal version of the scanner that starts around 250$us.

1. The ECM software is not multi threaded. It wants to either run the car or feed the scanner. If you do both you will throw off the timing, and some other functions. This is a limitation of GM ECMs! Not the scanning systems.
2. The Scanner can perform real time reporting of a running motor but because of the ECM designs, some cars may be undrivable while scanning. This limitation affects my 87 4cyl, but not so bad I couldn’t drive the car safely. Other years may be better or worse.
3. The Fiero ECM’s do not support scanner reset of error codes. You must use one of the 2 methods normally used that break power feeding the ECM from the battery.
4. The error trap mode available on the scanner may be of limited use because the ECM may not be drivable while scanning, and ECM processing is off spec during scanning. In this mode the scanner reads the data stream, and when the user presses enter the scanner records the 15 second or so of data on either side of the button press.