The best approach is to:
1. Consult your owner's manual: This is the most reliable source. The diagram should show the fuse box layout and identify the horn relay.
2. Open the fuse box: Locate the fuse box under the hood (usually near the battery).
3. Look for a large relay: Horn relays are typically larger than other relays in the box. You may see a diagram printed on the fuse box cover that shows the relay locations.
4. Check for markings: Some relays may be labeled "Horn" or have a horn symbol.
5. If unsure: If you can't find it visually, consult a Jeep Wrangler YJ wiring diagram online (available through various automotive forums and repair sites). These diagrams will show the relay's location within the circuit.
Remember to disconnect your battery's negative terminal before working on any electrical components in your vehicle to prevent short circuits.