Here's a breakdown of the wiring process:
1. Identifying the Alternator Wires:
Your alternator will have several wires:
* Large "B+" (Battery Positive): This is the main power output wire, usually thick and heavy gauge.
* Smaller "S" (Sense) or "IG" (Ignition): This wire provides the signal to the alternator to begin charging. It's crucial for regulation. It's sometimes a smaller gauge wire.
* Possibly a "W" (Warning) Lamp Wire: This wire connects to the alternator warning light on your dash. If your alternator lacks this wire, it might be internally regulated and integrated into the main charging system.
2. Alternator to Battery:
* Large "B+" wire: Connect this directly to the positive (+) battery terminal with a large-gauge wire and appropriate fuse (at least 100 amps, ideally closer to 150 amps) near the battery. This fuse is crucial to protect your wiring harness.
3. Sense/Ignition Wire Connection:
* Smaller "S" or "IG" wire: This wire needs to be connected to a switched 12V source, meaning a circuit that's only powered when the ignition is on. A good place to tap into this is the ignition switch itself (requiring some wiring knowledge and understanding of the car's wiring harness). Do not connect this wire to the battery directly. Connecting this directly to the battery will likely damage the alternator. Other locations might include a switched fuse in the fuse box or a wire from the ignition coil that is live only when the key is turned. Refer to a wiring diagram for your specific 1985 Mustang 5.0 to identify the correct location.
4. Warning Lamp Wire (If Applicable):
* "W" wire: If your alternator has a warning light wire, connect it to the alternator warning light in your instrument cluster. Again, consult your wiring diagram to locate the correct wire. This will light up if the alternator isn't charging.
5. Grounding:
The alternator case itself should have a good ground connection to the engine block. Ensure there is a clean, solid connection.
Important Considerations:
* Wiring Diagram: Obtain a wiring diagram specific to your 1985 Mustang 5.0. This will be invaluable in identifying the correct wire colors and locations. You can often find these diagrams online through forums dedicated to classic Mustangs or repair manuals.
* Fuse Protection: The fuse is paramount. A faulty alternator or short circuit could cause significant damage without it.
* Amperage: Choose an alternator with a sufficient amperage output for your system's needs. Too low and you may not have enough power, too high might overload your existing wiring.
* Professional Help: If you're uncomfortable with automotive electrical work, consider seeking the assistance of a qualified mechanic. Incorrect wiring can lead to serious damage to your vehicle's electrical system.
This information provides a general guideline. Always defer to the specific wiring diagram for your year and model Mustang to ensure proper installation. Using a multimeter to verify voltage and current during the process is highly recommended.
