2003-2004 Infiniti M45 Alternator Guide: Noises, Part Numbers, and Replacement
Diagnose common charging system problems and learn how to choose the correct used OEM alternator for your 4.5L V8.
- A failing alternator will typically cause both the battery and BRAKE warning lights to illuminate at the same time.
- Infiniti used two different alternators in 2004; you must match part number 23100-CR910 (early '04) or 23100-AR710 (late '04).
- A used OEM Mitsubishi alternator is a reliable choice, as failures are most common after 130,000 miles.
- It is unsafe to drive with a failing alternator, as the vehicle can stall without warning once the battery is depleted.
Symptoms of a Failing 2003-2004 M45 Alternator
When the alternator in your M45 begins to fail, it will provide several distinct warning signs. Because it powers the entire electrical system, symptoms can range from strange noises to a variety of electronic issues.
Warning Lights
The most common indicator is a warning light on your dashboard. You will likely see the battery-shaped warning light illuminate. On these M45 models, it's very common for both the battery light and the 'BRAKE' light to come on at the same time when there is a charging system fault. You may also see a "Charging System Warning" message on the center display.
Electrical Issues
A failing alternator struggles to provide consistent voltage. This can cause:
- Dimming or Flickering Headlights: Lights may dim when the engine is at idle and brighten as you accelerate.
- Slow or Malfunctioning Accessories: Power windows may roll up and down slowly, the radio might cut out, or heated seats may not work properly as the car's computer cuts power to non-essential systems.
- Dead Battery: An alternator that isn't charging properly will cause the battery to drain, even while driving. You may find yourself needing to jump-start the car frequently. If the car starts with a jump but dies shortly after, the alternator is the likely culprit.
Noises and Smells
Physical failure of the alternator's internal components can produce distinct sounds:
- Whining or Grinding Noise: A high-pitched whining or a grinding sound that changes with engine RPM points to worn-out bearings inside the alternator.
- Squealing Sound: A loud squeal, especially on startup or when under heavy electrical load (like turning on the A/C and headlights), can indicate a slipping serpentine belt, which is often related to the alternator pulley.
- Smell of Burning Rubber or Wires: A hot, burning smell can be caused by an overworked alternator or a misaligned pulley destroying the serpentine belt.
Known Issues, Recalls, and Technical Service Bulletins (TSBs)
As of mid-2026, there are no active recalls or TSBs specifically for the alternator on the 2003-2004 Infiniti M45.
However, these vehicles were subject to other important recalls you should be aware of:
- Fuel Gauge Inaccuracy (NHTSA Campaign R1208): A major safety recall was issued for a faulty circuit board that could cause the fuel gauge to read incorrectly, potentially leading to the vehicle running out of fuel and stalling. Dealers were instructed to modify the circuit board to correct the issue.
- Brake Lamp Switch Failure: A recall was issued for a malfunctioning brake lamp switch.
- Takata Airbag Inflators: Like millions of other vehicles, the M45 was included in the massive Takata airbag recalls.
Pro Tip: While not a recall, a common cause of premature alternator failure on many V8 engines is fluid contamination. Oil leaks from valve cover gaskets or power steering fluid leaks can drip onto the alternator, saturating its internal components and causing it to short out. When replacing the alternator, inspect the area above it for any signs of fluid leaks.
Buying a Used 2003-2004 M45 Alternator
A high-quality, low-mileage used OEM alternator is often a more reliable and cost-effective choice than a new aftermarket part. The original alternators for the M45 were manufactured by Mitsubishi, a top-tier OEM supplier known for durability.
Warning: Part Number Change in 2004. Infiniti used two different alternators during the 2003-2004 production run. It is critical to match the part number from your old alternator or verify compatibility by VIN. While the exact production date cutoff is unclear, the change occurred during the 2004 model year.
- Part Number: 23100-CR910 (Mitsubishi P/N: A3TG0191) - Typically fits 2003 and early 2004 models.
- Part Number: 23100-AR710 - Typically fits later 2004 models.
What to Inspect on a Used Alternator
- Physical Condition: Check the housing for any cracks, heavy corrosion, or signs of being dropped.
- Pulley: Spin the pulley by hand. It should spin smoothly and quietly. Any roughness, grinding, or wobble indicates bad bearings.
- Electrical Terminals: The main B+ terminal stud should be straight and the threads clean. Check the plastic connector housing for any cracks or broken tabs.
- Signs of Contamination: Look for dark, oily residue. An alternator caked in old oil is likely to have a shorter lifespan.
Mileage and Lifespan
The original Mitsubishi alternator can be very durable, with failures often occurring at well over 100,000 miles. Forum discussions show examples of alternators lasting between 130,000 and 200,000+ miles. When buying used, look for a part from a vehicle with the lowest mileage possible to ensure the longest remaining service life.
Cost Comparison for M45 Alternator Replacement
Prices can vary based on supplier and location. The original OEM part 23100-CR910 is largely discontinued, making used OEM and remanufactured units the most common options.
| Part Type | Estimated Price Range | Notes |
|---|---|---|
| New OEM | $600 - $900+ | Very difficult to find new. Prices reflect similar new OEM Infiniti alternators. |
| Remanufactured Aftermarket | $180 - $250 | Commonly available from stores like AutoZone and Advance Auto Parts. Core charge usually applies. |
| Used OEM | $75 - $150 | A cost-effective option. Price depends on mileage and condition. |
| Shop Labor | $180 - $270 | RepairPal estimates 1.5-2.5 hours of labor for this job. |
Alternator Replacement Overview
Replacing the alternator on the 4.5L VK45DE engine is achievable for a DIY mechanic with moderate experience. The alternator is accessible from the top of the engine bay. The job typically takes 1.5 to 2.5 hours.
Key Steps:
- Disconnect the battery's negative terminal. This is a critical safety step.
- Remove the engine cover, air intake ducting, and fan shroud cover to create space.
- Loosen the three bolts holding the power steering reservoir and move it aside (without disconnecting hoses).
- Release the serpentine belt tension and remove the belt from the alternator pulley.
- Disconnect the main electrical connector and the B+ terminal nut (typically 12mm) from the back of the alternator.
- Remove the two main mounting bolts (typically 12mm and 14mm) and remove the alternator from the vehicle.
- Installation is the reverse of removal.
Pro Tip: While the alternator is out, it's the perfect time to replace the serpentine belt. Also, inspect the belt tensioner and idler pulleys for any signs of wear or noise and replace them if necessary.
Important Torque Specs
Using correct torque is crucial to avoid damaging the alternator or bolts. These specs are based on the shared VK45DE engine platform; always verify with a factory service manual if possible.
| Component | Torque Spec | Source |
|---|---|---|
| Alternator Main Mounting Bolt | ~48 ft-lbs | |
| Alternator Bracket/Stay Bolt | ~21 ft-lbs | |
| B+ Terminal Nut (on alternator) | ~7 ft-lbs (84 in-lbs) |
Frequently Asked Questions (FAQ)
Can I drive my M45 with a bad alternator?
No. The vehicle will only run off the battery's reserve power for a very short time. Once the battery is depleted (which can happen in minutes), the engine will stall, and you will lose all power, including to safety systems. It is not safe to drive.
Why are my battery and brake warning lights on at the same time?
On many Nissan and Infiniti vehicles of this era, the charging system is linked to the brake warning light circuit. When the alternator's output voltage drops below a certain threshold, it triggers both the battery and brake warning lights simultaneously. This is a normal, albeit confusing, indicator of a charging system problem.
Should I buy a remanufactured alternator or a used OEM one?
A low-mileage used OEM Mitsubishi unit is often a better choice for fit and long-term reliability than a budget remanufactured part, which can have inconsistent quality. However, a premium remanufactured unit from a reputable brand can also be a good option and often comes with a lifetime warranty.
Is rebuilding my original M45 alternator an option?
Yes, rebuilding is possible. Kits containing common wear items like the voltage regulator, brushes, and bearings are available. This can be a cost-effective solution if you have the skills to disassemble and reassemble the alternator, but for most people, swapping the entire unit with a used or remanufactured part is faster and easier.
Technical Specifications
OEM Part Numbers: 23100-CR910 23100CR910 23100-AR710 A3TG0191
Voltage: 12V, Amperage: 110A, Pulley: 6-Groove Solid, Rotation: Clockwise
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- INFINITI M45:
- Symptoms of a Failing 2003-2004 M45 Alternator
- Warning Lights
- Electrical Issues
- Noises and Smells
- Known Issues, Recalls, and Technical Service Bulletins (TSBs)
- Buying a Used 2003-2004 M45 Alternator
- What to Inspect on a Used Alternator
- Mileage and Lifespan
- Cost Comparison for M45 Alternator Replacement
- Alternator Replacement Overview
- Key Steps:
- Important Torque Specs
- Frequently Asked Questions (FAQ)
- 🎟️ Get 5% Off