Toyota 86510-60190 Horn Assy, High Pitched

The left side of the radiator on 4Runner models has a horn built in. To verify the horn works, remove the electrical plug, attach jumper wire to two terminals, and send battery power through them; the horn must be replaced if you don't hear it. If the horn works when you push the button, look for short circuits between the horn and ground. When the voltage readings are zero, check the horn relay - the majority of these have either four terminals or an external ground with three terminals. When the relay works, test both power and control voltages and look for faulty wiring between it and your fuse panel if either circuit shows no voltage. When both relay circuits show voltage, press the horn button and look if current can flow from the relay to the ground by the button. If no current flows, check for broken or stuck wires. If none are found, change the button. When you have continuity, take a look for an electrical break or wrong connection between the relay and horn. Detaching and installing a new horn requires plugging off the electric connector, unscrewing the bracket bolt to remove the horn, rebolting the bracket to the new horn, and reversing these steps to put everything back.