1. Fuse:
* Check the fuse: This is the most common cause. Consult your owner's manual to locate the correct fuse for the horn and rear wiper. It's often a shared fuse. Visually inspect it; a blown fuse will have a broken filament. Replace it with a fuse of the same amperage rating. If the new fuse blows immediately, there's a short circuit somewhere in the system.
2. Fuse Block:
* Corrosion or damage: Even if the fuse looks okay, corrosion or damage within the fuse block itself could interrupt the circuit. Inspect the fuse block for any signs of corrosion, melted plastic, or loose connections.
3. Relay:
* Horn relay: The horn likely uses a relay to switch the high current needed. A faulty horn relay will prevent the horn from working.
* Rear wiper relay: Similarly, the rear wiper may have its own relay.
4. Wiring:
* Broken or corroded wires: Check the wiring harness leading to the horn and rear wiper motor for any broken, frayed, or corroded wires. Pay close attention to areas where the wires might rub against metal parts of the vehicle. This is especially true for the rear wiper, which is exposed to the elements.
* Connectors: Look at all the connectors for the horn and rear wiper motor. Ensure they are securely connected and free of corrosion.
5. Horn:
* Faulty horn: The horn itself might have failed. You can test this (carefully!) by applying 12V directly to the horn terminals. Be extremely cautious when doing this to avoid injury. If it works with direct power, the problem is elsewhere in the circuit.
6. Rear Wiper Motor:
* Faulty rear wiper motor: The motor might be seized, burned out, or have a faulty internal switch.
7. Multi-Function Switch (Steering Wheel):
* Faulty switch: The multi-function switch on the steering wheel controls the horn. If this switch is malfunctioning, it could prevent the horn from operating. This is less likely to affect the rear wiper, but it's possible depending on the wiring.
Troubleshooting Steps:
1. Check the fuse first. This is the easiest and most likely solution.
2. Visually inspect the wiring and connectors. Look for any obvious damage.
3. Test the horn directly (with extreme caution).
4. If the fuse keeps blowing, there's a short circuit. You'll need to carefully trace the wiring to find the short. This is best done by a professional if you're not comfortable with electrical systems.
5. Consider the relays. If the fuse is good and wiring seems okay, suspect relays. You may need a multimeter to test relays.
If you're not comfortable working with automotive electrical systems, it's best to take your Explorer to a qualified mechanic. Attempting repairs without the proper knowledge can lead to further damage or personal injury.
