1. Safety First!
* Disconnect the negative battery terminal before starting any electrical work. This prevents accidental shocks and short circuits.
2. Identify the Problem:
* No sound at all? This could be a blown fuse, a bad relay, a wiring problem, or a faulty horn itself.
* Weak or intermittent sound? This points more towards a wiring issue, a corroded connection, or a failing horn.
* One horn works, one doesn't? (Many Novas had dual horns). This isolates the problem to a single horn and its associated wiring.
3. Check the Fuse:
* Consult your owner's manual to locate the horn fuse. It's usually in the fuse box under the hood or inside the car (often under the dash).
* Visually inspect the fuse. A blown fuse will have a broken filament. Replace it with a fuse of the same amperage rating.
4. Inspect the Horn Relay (if applicable):
* Many vehicles use a relay to control the horn circuit. Locate the relay (often in the fuse box or under the dash) and check it visually for any damage. Some relays have a click test, where you can briefly energize the relay (carefully!) with a multimeter to check if it clicks. A faulty relay is often best replaced.
5. Check the Horn Wiring:
* Locate the horn(s): They're typically mounted on the radiator support or frame.
* Visually inspect the wiring: Look for any broken, frayed, or corroded wires leading to the horn(s). Pay close attention to the connectors. Clean any corrosion with a wire brush and electrical contact cleaner. Repair or replace any damaged wiring.
* Test the wiring with a multimeter: With the ignition ON, you should have power at the horn's positive wire when you press the horn button. Use the multimeter to test continuity from the horn button to the horn itself.
6. Test the Horn(s):
* Directly apply 12V: With the negative battery terminal still disconnected, carefully connect the positive lead of your battery (with a suitable jumper cable or similar) to the positive terminal of the horn. If the horn doesn't sound, it's likely faulty and needs replacement. Be extremely cautious to prevent shorts.
* Grounding: Ensure the horn has a good ground connection. Corrosion on the mounting bracket can prevent a proper ground.
7. Test the Horn Button/Steering Wheel Switch:
* Use a multimeter to check the continuity of the horn button circuit. This involves testing the circuit when the horn button is pressed. If no continuity, the switch may be faulty.
8. Replace Faulty Components:
* Replace any blown fuses, bad relays, damaged wiring, or faulty horns as needed. Auto parts stores sell replacements for all these components. Be sure to get the correct amperage fuse and relay.
Specific to 1978 Chevy Nova:
The exact location of the fuse box, relay, and horns might vary slightly depending on the trim level and options of your Nova. Refer to a wiring diagram specifically for a 1978 Chevy Nova to pinpoint these components accurately. A Chilton's or Haynes repair manual for your year and model is an invaluable resource. You can often find these online in PDF format or at auto parts stores.
Remember safety first! If you're not comfortable working with car electrical systems, it's always best to consult a qualified mechanic.
