* Clearing trouble codes: This is the most common reason people want to "reset" the ECM. The 1990 Suburban doesn't have an OBD-II port for easy computer access. To clear codes, you'll likely need to:
* Disconnect the battery: This is the simplest method. Disconnect the negative (-) terminal for at least 10-15 minutes. This will clear the short-term memory of the ECM, including trouble codes. Reconnect the battery and the system should run a self-test. This doesn't necessarily fix the underlying problem, only clears the stored code.
* Use a code reader: For a 1990 model, you'll need a code reader specifically designed for OBD-I (pre-OBD-II) systems. These are less common and often require knowledge of the specific vehicle's diagnostic connector and procedures. You will likely need to look up procedures specific to your Suburban's year and engine.
* Addressing a specific problem: If you're having a particular issue (e.g., stalling, rough idle), simply disconnecting the battery won't fix it. You need to diagnose and repair the underlying mechanical or electrical problem. Disconnecting the battery only clears the codes; it doesn't repair faulty sensors, wiring, or other components.
* After repairs: After replacing a sensor or other component, disconnecting the battery for 10-15 minutes is often recommended to allow the ECM to re-learn its parameters.
Important Considerations:
* Safety: Always disconnect the negative battery terminal first.
* Specifics: The exact method might vary slightly depending on the engine (e.g., 5.7L, 6.2L, etc.) in your 1990 Suburban. Consulting a repair manual specific to your vehicle's year and engine is highly recommended for precise instructions and diagnostic information. A Haynes or Chilton manual would be a good investment.
* Professional help: If you're uncomfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic for diagnosis and repair.
In short, disconnecting the negative battery terminal is the closest equivalent to a reset for a 1990 Chevy Suburban's ECM, but it's crucial to understand it only clears codes and doesn't fix underlying mechanical issues. For more advanced troubleshooting, a repair manual and possibly a specialized OBD-I scanner are needed.
