* Under the hood, in the fuse/relay box: This is the most likely location. The fuse/relay box is usually situated near the battery, often on the driver's side fender well. Check the diagram on the inside cover of the box to identify the horn relay.
* Under the dash: Less common, but possible. You might find it near the steering column or tucked away within the dashboard itself.
To find it definitively:
1. Consult your owner's manual: This is the best resource. It will have a diagram showing the location of all fuses and relays.
2. Look for a diagram on the inside of the fuse/relay box cover: Many fuse/relay boxes have a diagram printed on the inside of the cover. This will show the location and function of each relay.
3. Use a wiring diagram: You can find wiring diagrams online or through a repair manual specific to your 1990 F-250. These diagrams are very detailed and will show you exactly where the relay is and how it's wired.
Remember to disconnect the negative battery terminal before working with any electrical components to prevent accidental shorts or damage.
