Horn wiring diagram needed

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The horns are grounded to the body through the mounting bolts and the yellow with light green wire provides power to them. If you have cruise control the wiring uses a relay to trigger the power to the horns, if you do not have cruise you do not have a relay. On the models that do not have a relay there is a jumper block that plugs into the wiring where the relay normally goes.
Easiest way to test would be to connect a high draw test light (headlight bulb works well) in place of the horns. That way you can test if the circuit can carry enough current to make the horns sound. A normal test light does not provide enough draw to be sure.