SEC codes

Is there a way to reset the Service engine soon light and clear the codes to see if they get set again?

About 3 months ago, I was having tranny problems and needed to disconnect the transmission from the computer because of eratic shifting problems. I put a different tranny in, but the service engine soon light stays on.

Thanks.

Unplug the battery for half hour. Or take the car to Autozone and have them scan it and clear the codes.