How do you Read codes on a 1989 Volvo 760 with 2.3 turbo?

To read codes on a 1989 Volvo 760 with a 2.3 turbo, locate the diagnostic connector under the dashboard near the driver's side. Use a jumper wire to connect terminals A and B on the connector. Turn the ignition key to the "on" position without starting the engine, and the check engine light will blink the trouble codes in a sequence. Count the blinks to identify the codes, referring to the vehicle's service manual for their meanings.