How can you read codes on 1990 Mitsubishi mighty max with no scanner?

To read trouble codes on a 1990 Mitsubishi Mighty Max without a scanner, you can use the diagnostic connector under the dash. Connect a jumper wire between terminals A and B of the connector, then turn the ignition key to the "On" position without starting the engine. The check engine light will begin to blink, with a series of long and short flashes indicating the specific trouble codes. Count the blinks to decipher the codes, which can then be referenced in a repair manual for troubleshooting.