1. Ground terminals A and B (see diagram below at first link below) with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A Code 12 consists of one flash, a short pause, then two flashes in rapid succession.

2. After Code 12 is displayed, any stored trouble codes will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All codes are displayed 3 times each then a code 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.

http://www.obd-codes.com/fa...t-obd-codes-free.php

GM 2 Digit Trouble Codes
http://www.obd-codes.com/tr...gm-2-digit-codes.php

https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

I would say that's almost correct for the Fiero. You can use a paper clip shaped into a U to ground A and B. But, When inserting or removing the clip, the ignition should be OFF. Once inserted, turn the ignition ON but don't start and it will go through the described sequence of flashes. Once the loop goes back to 1 Flash-2 Flash, turn the ignition OFF and remove the paper clip.

The diagram in your link shows the diagnostic port installed upside down to what it is in the Fiero. The A and B terminals are on the lower level, passenger side of the ALDL.

[This message has been edited by fierofool (edited 01-26-2014).]

See my Cave, ALDL/ALCL

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)