Need horn wiring diagram so I know what wires to check for nonworking horn.
Aug 27, 2018 at 11:30 PM
Horn wiring diagram needed
1990 FORD F-450
HAROLD BOHLIN
- MEMBER
- 1 POST
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STEVE W.
- ✓ASE Certified Mechanic
- 15,200 POSTS
Welcome to 2CarPros.
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.
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.
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Aug 28, 2018 at 10:18 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.