Bench Checks

1. Measure current draw of horn while horn is operating. Current draw for each horn should be between 4.5 and 5.5 amps at 11.5 to 12.5 volts.
2. No current may indicate a broken connection or an open circuit due to a broken lead or overheating. Most horn problems are caused by horns being operated continuously, developing sufficient heat to melt the wires in the winding, causing an open circuit.

Overheating is accompanied by a characteristic odor which indicates that the horn has overheated and should be replaced.
1. No current can also indicate that the contact points are open and a current adjustment is required.
2. High current, over 20 amperes, indicates a shorted horn which should be replaced.
3. A reading of approximately 18 amps for a 12-volt horn indicates a condition in which the contact points are not opening. A current adjustment is required.