Where is the ecm on a 1986 S10 Chevy pickup truck?

On a 1986 Chevy S10, the Engine Control Module (ECM) is typically located under the hood, on the driver's side fender apron. It's often mounted to the inner fender itself, sometimes behind a cover or heat shield. It's a fairly small, rectangular box.

However, the exact location might vary slightly depending on the engine and options on your specific truck. It's best to check your owner's manual (if you have it) or consult a repair manual for your year and model S10 to be absolutely certain. You can also find diagrams online showing the location of the ECM for a 1986 S10. Be sure to specify the engine size (e.g., 2.8L, 4.3L) in your search for the most accurate results.