GM 84501937 Horn Assembly, Dual

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Check the fuses before beginning electrical diagnosis. Disconnect the electrical connector from the horns. To test the horns, connect battery voltage and ground to the horn terminals with a pair of jumper wires. If either horn doesn't sound, replace it. If the horn does sound, check for voltage at the horn connector when the horn switch is depressed. Check for voltage at the horn while an assistant pushes the horn button. If there's voltage at the connector, check for a bad ground at the horn. If there's no voltage at the horn, check the relay. If the relay is OK, check for voltage to the relay power and control circuits. If either of the circuits is not receiving voltage, inspect the wiring between the relay and the fuse panel. If both relay circuits are receiving voltage, depress the horn switch and check the circuit from the relay to the horn switch for continuity to ground. If there's no continuity, check the circuit for an open. If there's no open circuit, replace the horn switch. If there's continuity to ground through the horn switch, check for an open or short in the circuit from the relay to the switch. If the horn works, but the tone is off, either weak or strained, check the current draw of the horn, using an ammeter during operation. Hook the ammeter between the horn connector and the terminal on the horn. A correctly operating horn should draw 4.5 to 5.5 amps. Use the adjusting screw on the horn to achieve this draw. The horn on is located in the fenderwell. Raise the vehicle and support it securely on jackstands. Remove the front wheel and the fenderwell splash shield for access. Disconnect the electrical connectors and remove the bracket bolts. Installation is the reverse of removal. Make sure the area of the body is clean where the horn bracket attaches. This is the ground point for the horn.