How to Reset the Computer on a 1990 Lumina
- 1). Open the hood to the Chevy Lumina.
- 2). Disconnect the negative battery terminal bolt from the side-post battery. The negative battery terminal bolt is the cable and bolt assembly colored with a black plastic cover over the end of the cable attached to the battery. Use the 8 mm closed-end wrench to turn the bolt counterclockwise until it disconnects.
- 3). Unsnap the red plastic cover protecting the positive battery terminal bolt and cable assembly (if equipped). Disconnect the positive battery terminal bolt using the 8 mm wrench.
- 4). Turn on the interior headlight switch for 10 minutes to discharge any possible stored voltage in the battery's capacitor. This will erase the computer memory and reset it.
- 5). Connect the red, positive battery terminal bolt to the side-post of the battery first and tighten it with the wrench in a clockwise motion. Replace the cap (if equipped).
- 6). Connect the black, negative battery terminal bolt last (removing and replacing the terminal bolts as denoted will help prevent the chance of sparks occurring, which could ignite gas vapors emitting from the battery and cause an explosion). Tighten the bolt with the wrench.
- 7). Start the engine to ensure the service engine soon light is no longer illuminated. If it is, or if it comes back on after a few normal driving cycles, have the Lumina computer DTCs diagnosed and the repairs performed before trying to reset the computer again. The engine idle may run rough for a few small driving cycles due to the idle memory being reprogrammed when the computer was reset. This will be a temporary side-effect.
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