Here's how to find it:
1. Open the hood of your truck.
2. Look on the passenger side of the engine compartment. The ECM is usually mounted on the firewall, which is the metal panel that separates the engine compartment from the passenger cabin.
3. The ECM is a rectangular black box with wires and connectors. It may be covered by a plastic shield or shroud.
Note: There might be slight variations in the location depending on the engine and trim level of your specific truck. If you are unsure, you can consult your owner's manual or a repair manual for your 1993 Chevy 1500.