2012 Ford Fusion Se Fuse Box Diagram

Let's dive into the 2012 Ford Fusion SE's fuse box diagram. Whether you're dealing with a blown fuse, planning some electrical modifications, or simply trying to understand your car's electrical system better, this diagram is an essential tool. It acts as a roadmap, guiding you through the intricate network of circuits that power your Fusion.

Purpose of the Fuse Box Diagram

The fuse box diagram serves several critical purposes:

• Troubleshooting Electrical Issues: When an electrical component malfunctions (e.g., a non-working interior light, a dead cigarette lighter), the first thing to check is the corresponding fuse. The diagram tells you precisely which fuse to inspect.
• Preventing Further Damage: Replacing a blown fuse with one of the correct amperage protects sensitive electronic components from overcurrent situations. Using a higher amperage fuse than specified can lead to serious damage and even fire.
• Planning Electrical Modifications: If you're adding aftermarket accessories (like a new stereo, auxiliary lights, or a remote starter), you need to identify appropriate power sources and understand the existing circuit protection. The diagram shows available circuits and their associated fuses.
• General Understanding: Even if you don't have immediate problems, studying the diagram gives you a deeper understanding of your vehicle's electrical architecture.

Key Specs and Main Parts of the Fuse Box

The 2012 Ford Fusion SE has at least two main fuse boxes:

• Battery Junction Box (BJB): Located in the engine compartment, typically near the battery. This box houses higher-amperage fuses and relays that control major systems like the starter motor, fuel pump, and headlights.
• Smart Junction Box (SJB): Located inside the passenger compartment, often under the dashboard or behind a kick panel. This box manages lower-amperage circuits for things like interior lights, the radio, and power windows. The SJB may also integrate with the car's central computer and Body Control Module (BCM).

Key components you'll find in these boxes include:

• Fuses: These are sacrificial devices designed to break the circuit when the current exceeds a safe level. They come in various amperage ratings, typically ranging from 5A to 40A or higher. Common types include blade fuses (ATO/ATC), mini-blade fuses, and cartridge fuses.
• Relays: Electrically operated switches that allow a low-current circuit to control a high-current circuit. For example, a relay might use a small switch on the dashboard to activate the high-current circuit for the headlights.
• Circuit Breakers: Similar to fuses, but resettable. They trip when the current exceeds a certain level and can be manually reset once the overload condition is resolved.
• Diodes: One-way electrical valves that allow current to flow in only one direction. They are often used to protect sensitive electronic components from reverse voltage.

Understanding the Fuse Box Diagram Symbols

Fuse box diagrams use a standardized set of symbols to represent different components and circuit characteristics. Familiarizing yourself with these symbols is crucial for interpreting the diagram correctly.

• Lines: Solid lines represent wires, and their thickness may sometimes indicate the wire gauge (thicker lines = thicker wires). Dashed lines often indicate a ground connection.
• Colors: Wire colors are usually indicated next to the lines on the diagram. This is extremely important when tracing wires in the vehicle. Common abbreviations include:
  • BK: Black
  • RD: Red
  • WH: White
  • BL: Blue
  • GN: Green
  • YE: Yellow
• Fuse Symbols: Fuses are typically represented by a wavy line inside a rectangle. The amperage rating is often indicated next to the fuse symbol (e.g., "20A").
• Relay Symbols: Relays are usually depicted with a coil symbol (representing the electromagnet) and a switch symbol (representing the contacts).
• Ground Symbols: Represented by three descending lines, indicating a connection to the vehicle's chassis (ground).
• Component Symbols: Simplified drawings of the actual components (e.g., a light bulb, a motor, a sensor).

The diagram also includes labels indicating the circuit's function. For example, "PCM IGN" might indicate the fuse for the Powertrain Control Module (PCM) ignition circuit.

How the Fuse Box Works: A Simplified Explanation

Think of the fuse box as a central distribution panel for electrical power. The battery provides the initial electrical energy. This energy flows through the main power cables to the BJB and SJB. From there, the power is distributed to various components throughout the vehicle via individual circuits, each protected by a fuse.

Each circuit has a specific amperage rating, determined by the load it's designed to handle. When a component draws excessive current (due to a short circuit, a malfunction, or overloading), the fuse blows, breaking the circuit and preventing further damage. The fuse element – a thin strip of metal inside the fuse – melts when the current exceeds its rating.

Relays act as intermediaries, allowing low-current switches to control high-current devices. When the low-current switch is activated, it energizes the relay's coil, which closes the relay's contacts, completing the high-current circuit and powering the desired component.

Real-World Use: Basic Troubleshooting

Here’s a simple troubleshooting scenario:

1. Problem: The radio is not working.
2. Check the Diagram: Consult the fuse box diagram for the SJB to identify the fuse associated with the radio. Look for labels like "Radio," "Audio," or "ACC (Accessory)."
3. Locate the Fuse: Find the fuse in the SJB corresponding to the diagram's location.
4. Inspect the Fuse: Visually inspect the fuse. If the metal strip inside is broken or blackened, the fuse is blown.
5. Replace the Fuse: Replace the blown fuse with a new fuse of the same amperage rating. Never use a higher amperage fuse.
6. Test: Turn on the radio to see if it works. If the fuse blows again immediately, there's likely a short circuit in the radio or its wiring, requiring further investigation.

If a fuse keeps blowing repeatedly, it's crucial to identify the root cause of the overcurrent. Don't simply keep replacing fuses without addressing the underlying problem. This can lead to serious electrical damage and potentially a fire.

Safety Considerations

Working with automotive electrical systems can be dangerous. Always follow these safety precautions:

• Disconnect the Battery: Before working on any electrical components, disconnect the negative (-) terminal of the battery. This will prevent accidental short circuits and shocks.
• Use Proper Tools: Use insulated tools designed for automotive electrical work.
• Avoid Water: Never work on electrical systems in wet conditions.
• Be Careful with Relays: Relays can sometimes be hot after the car has been running. Let them cool down before handling them.
• High-Risk Components: Be especially careful when working around the BJB, as it contains high-amperage fuses and relays that control critical systems. Never bypass a fuse with a piece of wire. This removes the circuit protection and can lead to a dangerous overload.

Identifying the correct fuse and ensuring you're using a replacement with the proper amperage is key. Consult the diagram to avoid potentially costly mistakes. Understanding how the electrical system of your 2012 Ford Fusion SE works is valuable for both maintenance and customization.

We have the complete fuse box diagram available for download. With it, you'll be well-equipped to tackle basic electrical troubleshooting and modifications on your 2012 Ford Fusion SE.