What you likely need to do depends on what you're trying to achieve:
* Clear trouble codes (check engine light): You'll need to use a code reader (OBD-II scanner) to read and clear the diagnostic trouble codes (DTCs). Auto parts stores often offer free code reading services. Alternatively, you can buy a relatively inexpensive OBD-II scanner for home use. Simply clearing codes won't fix the underlying problem, though – it only clears the light.
* Reset the PCM: This is more involved and generally only done by disconnecting the battery's negative terminal for a period of time (around 15-30 minutes). This can sometimes reset the PCM, but it's not guaranteed to solve all problems. *Caution:* Make sure to disconnect the negative terminal first to avoid short circuits. Also, disconnecting the battery will erase any personalized settings (radio presets, clock, etc.).
* Something else? If you're experiencing a specific problem (e.g., erratic shifting, stalling), "resetting the computer" is unlikely to solve the issue. The problem will likely require proper diagnosis and repair.
In short, there's no simple "reset" button. Use a code reader to address trouble codes, or disconnect the battery for a more thorough (but less precise) reset of the PCM. If you have a specific issue, providing more details will allow for better assistance.
