How do you read trouble codes in a 1991 Oldsmobile ninety-eight?

To read trouble codes in a 1991 Oldsmobile Ninety-Eight, you need to locate the diagnostic connector, typically found under the dashboard near the steering column. Use a jumper wire to connect terminals A and B of the ALDL (Assembly Line Diagnostic Link) connector. Then, turn the ignition key to the "On" position without starting the engine; the check engine light will blink the trouble codes in a series of flashes. Count the flashes to interpret the codes, which can be referenced in a repair manual for further diagnosis.