Where is the computer on a 1999 GMC Yukon?

In a 1999 GMC Yukon, the engine control module (ECM), commonly referred to as the computer, is typically located under the hood, near the driver's side fender. It is housed in a metal casing and is mounted against the firewall. You may need to remove some components or covers to access it fully. The ECM is responsible for managing engine performance and various vehicle systems.