I know you can unplug the 3 PCM connectors to do it quickly, but since I'm lazy I wanted to know if just disconnecting the positive cable in the engine bay will work? How long will it take? I tried it before and it still did not reset after 45 minutes.
I think I might have misunderstood your original question. To reset the computer (so it goes back into learn mode), I disconnect the power plug above the PCM, but I don't do this to reset an SES light. I've never had an SES light on my car.