How do you check codes on 1994 Pontiac firebird?

To check the trouble codes on a 1994 Pontiac Firebird, start by turning the ignition key to the "On" position without starting the engine. Then, locate the diagnostic connector under the dash, usually near the steering column. Use a jumper wire to connect terminals A and B on the connector, and the Check Engine light will begin to flash, indicating the stored trouble codes. Count the flashes to interpret the codes, which can then be referenced in a repair manual or online for further diagnosis.