How do you reset the computer on Chevrolet express 1999?

A 1999 Chevrolet Express van doesn't have a "computer" in the same way a modern car does with a central control unit that can be easily reset. It has various electronic control modules (ECMs) – for the engine, transmission, etc. – that might require resetting depending on the problem. There's no single "reset" button.

What are you trying to accomplish by resetting the computer? Different problems require different solutions. For example:

* Engine light is on (Check Engine Light): This indicates a fault code stored in the Powertrain Control Module (PCM). You'll need a scan tool (OBD-II reader) to read the code, and then address the underlying issue. Simply disconnecting the battery won't fix the problem; it might clear the code temporarily, but the light will likely come back on until the problem is fixed.

* Intermittent electrical problems: Disconnecting the battery's negative terminal for a few minutes (30-60 minutes) is often a first step to reset various systems. This allows capacitors to discharge and can clear minor glitches. Reconnect the negative terminal last.

* Other issues (e.g., radio, power windows): These might involve fuses, relays, or other specific components. You'll need to consult your owner's manual to diagnose the issue and find a solution.

In short: Instead of trying to "reset the computer," describe the *specific problem* you're experiencing with your 1999 Chevrolet Express. Then, we can offer more tailored advice.