- 1). Open the hood of the Nissan truck and locate the round-shaped horn on the upper side of the firewall. Locate the bracket that secures the horn in place and the wire connectors on the bottom of the horn.
- 2). Loosen the bracket using the screwdriver and loosen the screws that secure the wires to the horn's connectors. Pull the wires from the connectors, then pull the horn off the firewall.
- 3). Place the new horn into the bracket on the firewall and tighten the bracket using the screwdriver, securing the new horn to the firewall. Replace the wires on their corresponding connectors and tighten the screws.
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