Your best bet is to:
1. Consult a 1977 Corvette wiring diagram: A factory service manual (FSM) is your best resource. These diagrams show the relay's location and associated wiring. You can often find these manuals online through sellers specializing in automotive repair manuals or at used bookstores.
2. Trace the horn wires: Start at the horn itself. Follow the wires back towards the fuse box and other components under the dash. The relay will be somewhere in that circuit. Look for a small, square or rectangular component with multiple terminals. It's likely to be in a relatively accessible area under the dash.
3. Check common locations for relays in classic cars: While not guaranteed for your specific model year, relays in older vehicles are often found:
* Under the dash: This is the most probable location.
* In the fuse box: Some fuse boxes incorporate relays.
* In the engine compartment: Less likely for the horn relay, but possible.
Remember to disconnect the battery negative terminal before working with any electrical components to avoid short circuits. Be careful not to damage any wiring while tracing the wires.
