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1989 is OBDI so you do not need a scanner to retreive codes. You connect a jumper wire between two terminals on the OBDI plug. The Service Engine light will flash a Morse Code like sequence. It will repeat each one 3 times starting with 1-2, 1-2, 1-2, then any codes will flash. When all codes are done the 1-2 will repeat. Look up the codes in a Haynes manual or even online. WaLa,, you are all done. Good Luck.