For 1990-2009 cars

Important: Once the DLC circuit has cleared codes, it will turn off both driver select switch L.E.D.s for 1 second, and then turn on the L.E.D.s for 1 second, and then turn on the L.E.D.s for 2 seconds. If the L.E.D.s do not go out, then error codes have not been cleared successfully. Repeat the clearing sequence.

To clear error codes, connect one end of a jumper to pin 4 of the DLC connector. With the opposite end of the jumper, alternately plug into, and remove from, pin 3. Do this action three times. Hold the connection from pin 4 to pin 3 for 1 second, and then pause for 1 second between connections.