Case 590 Super N Charging Failure and Electrical Diagnosis

[MikePhua]

The Case 590 Super N and Its Electrical System
The Case 590 Super N backhoe loader, launched in the early 2010s by CNH Industrial, was designed to meet Tier 4 emissions standards while delivering enhanced hydraulic performance and operator comfort. With a turbocharged 4.5L diesel engine, advanced load-sensing hydraulics, and a redesigned cab, the 590 Super N became a flagship model in Case’s loader-backhoe lineup. It was widely adopted by municipalities, contractors, and utility crews across North America and Europe, with thousands of units sold within its first five years.
One of the key upgrades in the Super N series was the integration of a 120-amp Iskra alternator, responsible for maintaining battery charge and powering onboard electronics. While robust, this alternator system has occasionally presented diagnostic challenges, particularly when charging failure occurs without obvious mechanical damage.
Symptoms of Charging Failure and Initial Observations
A common issue reported by operators is the battery not charging despite the alternator appearing intact. In one documented case, the alternator’s high-current output wire showed battery voltage, and the alternator casing was properly grounded. However, the machine still failed to charge, and the battery drained during operation.
Terminology annotation:
- Alternator: A device that converts mechanical energy into electrical energy to charge the battery and power electrical systems.
- Voltage regulator: A component that controls the alternator’s output voltage to prevent overcharging or undercharging.
- Excitation circuit: A low-voltage signal that activates the alternator’s field coil, allowing it to begin generating current.
- Tachometer feed: A signal wire that transmits alternator RPM data to the dashboard tachometer.
The alternator featured a three-wire plug: the center terminal received 12V when the ignition was on, while the two outer terminals showed no voltage or ground. This configuration suggested that the center wire served as the excitation source, while the outer wires fed data to the tachometer and hour meter.
Testing and Diagnostic Strategy
To avoid unnecessary replacement, technicians recommend bench testing the alternator before purchasing a new unit. A competent rebuild shop can test the alternator for free, checking field coil resistance, diode integrity, and regulator function. If the alternator fails to produce voltage under load, it is likely internally damaged.
Steps for field diagnosis:

• Confirm 12V excitation at the center terminal with ignition on.
  
• Check continuity and voltage at the high-current output terminal.
  
• Inspect ground connection between alternator case and chassis.
  
• Verify that the voltage regulator is receiving and responding to excitation.
  
• Test tachometer and hour meter function to ensure signal wires are intact.
  

If all wiring checks out and the alternator still fails to charge, replacement is warranted.
Understanding the Excitation Circuit
The excitation circuit is critical to alternator function. Without a proper signal, the field coil remains inactive, and the alternator does not generate current. In the Case 590 Super N, the ignition switch sends 12V to the center wire of the regulator plug, which in turn activates the alternator.
If this wire is damaged, corroded, or disconnected, the alternator will not “wake up.” This is a common oversight during troubleshooting, especially when focusing solely on the output terminal.
Solutions:

• Use a test light or multimeter to confirm voltage at the excitation wire.
  
• Clean and reseat all connectors with dielectric grease.
  
• Replace damaged wires with automotive-grade conductors rated for vibration and heat.
  
• Inspect fuse panel and ignition switch for intermittent faults.
  

Alternator Replacement and Compatibility
If replacement is necessary, ensure the new alternator matches the original Iskra unit in amperage, mounting pattern, and plug configuration. Some aftermarket units may use internal regulators or different excitation schemes, requiring wiring modifications.
Recommendations:

• Choose OEM or high-quality aftermarket units with verified compatibility.
  
• Confirm pulley diameter and belt alignment to prevent slippage.
  
• Torque mounting bolts to manufacturer specs to avoid vibration-induced failure.
  
• After installation, test charging voltage at idle and under load. Typical output should range from 13.8V to 14.4V.
  

Field Anecdotes and Operator Experience
One operator in Pennsylvania discovered that his alternator was not charging due to a failed internal regulator, despite all wiring being intact. After replacing the unit, the machine returned to normal operation. He noted that the tachometer and hour meter also resumed function, confirming that the outer wires were signal feeds rather than power sources.
Another technician in Arkansas emphasized the importance of avoiding the “dartboard approach” to diagnostics—randomly replacing parts without confirming failure. He recommended always testing components before ordering replacements, especially in systems with multiple interdependent circuits.
Preventative Maintenance and Electrical Reliability
To prevent future charging issues:

• Inspect alternator wiring quarterly for signs of wear, corrosion, or rodent damage.
  
• Clean battery terminals and check for proper grounding.
  
• Replace worn belts and tensioners to maintain pulley engagement.
  
• Monitor dashboard voltage readings and investigate sudden drops or spikes.
  
• Use sealed connectors and protective loom in high-vibration areas.
  

For machines operating in wet or dusty environments, consider upgrading to waterproof connectors and adding a splash shield around the alternator.
Case Construction Equipment and Electrical Evolution
Case, originally founded in 1842, has evolved into a global manufacturer of construction equipment under CNH Industrial. The 590 Super N represents a modern interpretation of the classic loader-backhoe, integrating emissions compliance, electronic monitoring, and improved hydraulic control.
While newer models feature CAN bus systems and diagnostic ports, the Super N retains enough mechanical transparency to allow field repairs without proprietary software. This blend of modern performance and serviceability continues to make it a favorite among operators who value both power and practicality.
Conclusion
Charging failure in the Case 590 Super N is often rooted in alternator excitation issues or internal regulator faults. Through methodical testing, wiring inspection, and component verification, operators can resolve the problem without unnecessary expense. In the world of heavy equipment, understanding the interplay between voltage, signal, and mechanical rotation is key to keeping machines running—and earning—day after day.