2020 Ford Mustang: How to Diagnose and Fix Alternator Issues

How to Fix Alternator Issues

The 2020 Ford Mustang can sometimes experience alternator-related problems, leading to frustrating electrical issues. These problems can manifest in various ways, from warning lights to complete battery drain. As one owner shared, "Batteries just don't last the way they used to. I'm surprised that the additional load from the AC compressor would have required battery power... the amperage from the alternator should have been more than enough."

Symptoms

Owners of this vehicle have reported several symptoms that point towards alternator issues. These symptoms aren't always immediately obvious but can escalate quickly if left unchecked. One common sign is unusual electrical noise. You might notice static in your radio or flickering lights, even when the engine is running at a consistent speed. This is often a subtle indicator that the alternator isn't providing a stable power supply.

Another symptom is the presence of electrical "gremlins." This vague term covers a range of unpredictable electrical malfunctions. For example, you might experience intermittent failures of power windows, the infotainment system, or even the PCM. These glitches can be random and difficult to trace, making diagnosis challenging.

Corrosion, particularly around the battery terminals and alternator connections, is another red flag. Corrosion can impede the flow of electricity, causing the alternator to work harder than it should. This added strain can lead to premature failure of the alternator and other electrical components. Regular inspection and cleaning of these connections are crucial for maintaining a healthy electrical system.

A parasitic draw, where the vehicle continues to draw power even when it's turned off, is another indicator. This can drain the battery overnight or over a few days of inactivity. While a parasitic draw can be caused by various components, a faulty alternator diode pack is a common culprit. If you suspect a parasitic draw, it's essential to identify the source quickly to prevent battery damage.

Most Likely Cause

Based on owner reports, a failing MAF (Mass Airflow) sensor is a likely cause indirectly impacting the alternator's performance. While not directly an alternator issue, a faulty MAF sensor can cause the engine to run inefficiently, placing undue stress on other components like the alternator. If the engine requires more power due to incorrect air/fuel mixtures, the alternator is forced to work harder, potentially leading to premature failure or unusual behavior.

A malfunctioning MAF sensor sends incorrect data to the engine's computer (PCM), which in turn can affect the charging system. The PCM controls various aspects of the engine's operation, including the alternator's output. If the PCM is receiving inaccurate information from the MAF sensor, it might not properly regulate the alternator, leading to undercharging or overcharging of the battery. As one owner shared, "Stock is best unless racecar/you are prepared to deal with the potential/realized problems from being non-stock. And with that, I agree on the MAF fouling."

How to Diagnose

Diagnosing potential alternator issues in your vehicle requires a systematic approach. Start by visually inspecting the alternator and its connections. Look for signs of corrosion, damaged wiring, or loose connections. Clean any corrosion you find with a wire brush and battery terminal cleaner.

Next, use a multimeter to test the alternator's output voltage. With the engine running, the voltage should be between 13.5 and 14.5 volts. A reading outside of this range indicates a potential problem with the alternator. Be sure to test the voltage both at the alternator and at the battery terminals to rule out any voltage drop in the wiring.

If the voltage readings are within the acceptable range, but you're still experiencing symptoms, consider testing the MAF sensor. You can use an OBD-II scanner to check for any MAF sensor-related trouble codes. If codes are present, further testing of the MAF sensor may be necessary.

Tools needed for diagnosis:

• Multimeter
• OBD-II scanner
• Wire brush
• Battery terminal cleaner
• Wrench set

Step-by-Step Fix

Addressing alternator-related issues in your vehicle often involves replacing the MAF sensor or the alternator itself. Here's a step-by-step guide:

1. Gather Your Tools and Parts: Make sure you have the necessary tools, including a wrench set, socket set, screwdrivers, and a new MAF sensor (if applicable) or alternator.

2. Disconnect the Battery: Before starting any electrical work, disconnect the negative battery cable to prevent shorts and electrical shocks.

3. Locate the MAF Sensor: The MAF sensor is typically located in the intake air duct between the air filter and the throttle body.

4. Disconnect the Electrical Connector: Carefully disconnect the electrical connector from the MAF sensor.

5. Remove the MAF Sensor: Use a screwdriver or wrench to remove the screws or clamps holding the MAF sensor in place.

6. Install the New MAF Sensor: Install the new MAF sensor in the reverse order of removal. Ensure the electrical connector is securely attached.

7. If Replacing the Alternator: Locate the alternator, typically at the front of the engine. Disconnect the electrical connections and remove the belt. Remove the mounting bolts and carefully remove the old alternator.

8. Install the New Alternator: Install the new alternator in the reverse order of removal. Make sure the belt is properly tensioned.

9. Reconnect the Battery: Reconnect the negative battery cable.

10. Test the Vehicle: Start the engine and use a multimeter to verify the alternator is charging correctly. Check for any error codes using an OBD-II scanner and clear them if necessary. As one owner shared: "Voltmeter fluctuation alongside the full suite of warning lights says the recently replaced alternator fits the backronym version of new; Never Even Worked." (Outcome: fixed)

Parts and Tools Needed

• MAF Sensor (if applicable): Varies based on brand.
• Alternator: Varies based on brand.
• Wrench set
• Socket set
• Screwdrivers
• Multimeter
• OBD-II scanner
• Battery terminal cleaner
• Wire brush

Real Owner Costs

The cost of addressing alternator issues can vary significantly depending on whether you choose to DIY or hire a professional mechanic.

• DIY MAF Sensor Replacement: The cost of a new MAF sensor can range from $50 to $200. If you perform the replacement yourself, you'll save on labor costs. As one owner mentioned, finding a stock one at a pull-a-part could cost as little as $20.
• DIY Alternator Replacement: A new alternator can cost between $150 and $400. DIY replacement can save on labor, but it requires a good understanding of automotive mechanics.
• Professional MAF Sensor Replacement: Expect to pay between $150 and $350 for professional MAF sensor replacement, including parts and labor.
• Professional Alternator Replacement: Professional alternator replacement can cost between $300 and $600, including the cost of the alternator and labor.

Prevention

Preventing alternator issues involves regular maintenance and proactive care. Keep the battery terminals clean and free of corrosion. Regularly inspect the alternator belt for cracks or wear and replace it as needed. Avoid overloading the electrical system with excessive aftermarket accessories.

What Owners Say

Real experiences from FORD owners:

Success Stories

"Voltmeter fluctuation alongside the full suite of warning lights says the recently replaced alternator fits the backronym version of new; Never Even Worked." — RJsRX7 (source)

Owner Experiences

"Batteries just don't last the way they used to. I'm surprised that the additional load from the AC compressor would have required battery power... the amperage from the alternator should have been more than enough." — LabCat62 (source)

"I'm surprised that the additional load from the AC compressor would have required battery power... the amperage from the alternator should have been more than enough." — LabCat62 (source)

"Stock is best unless racecar/you are prepared to deal with the potential/realized problems from being non-stock. And with that, I agree on the MAF fouling." — houtex727 (source)

Lessons Learned

⚠️ "They created electrical noise that messed with the sine wave of the DC voltage and confused the PCM , thus it threw the code. An alternator can charge just fine but still have a failing rectifier." — Derf00 (source)

Real Repair Costs

"Unless you have need for that oiled filter setup, toss it directly in the trash. Find a stock one at a pull a part, they'll be like 20 bucks if that probably." — houtex727 (source)

FAQ

Q: How long does it take to fix an alternator issue?

A: Replacing a MAF sensor can take 30 minutes to an hour for a DIY repair. Alternator replacement can take 1-3 hours, depending on your experience level. Professional repair times are typically shorter, but factor in shop availability.

Q: Can I drive with an alternator issue?

A: Driving with a failing alternator is not recommended. The vehicle will eventually drain the battery and leave you stranded. It's best to address the issue as soon as possible.

Q: Is this a common issue on the 2020 Ford Mustang?

A: While not the most common issue, alternator problems can occur, especially with higher mileage. Regular maintenance and inspections can help prevent these issues.

Q: DIY vs mechanic - what's recommended?

A: If you're comfortable with basic automotive repairs and have the necessary tools, replacing the MAF sensor or alternator yourself can save money. However, if you're not experienced, it's best to seek professional help to avoid further damage or injury. "Get a jump and then head to an auto parts store they can test your battery and alternator for free and will even replace your battery for you if needed," advised one owner.