[wiswind]

Disconnecting the battery, and leaving it disconnected for a while will make the CEL go out. It will also clear the "drivability" information. When this happens, you may notice less than optimum shift points, and other minor drivability issues while the PCM relearns the drivability information.
It does not take very long for the PCM to relearn the driveability information, but don't be concerned if it is not "just perfect" right away. It will NOT be a major issue, like rough running, or anything like that.....more like...not downshifting or upshifting at exactly the same time that you are used to.