Massey Ferguson 520200.16 – Engine ECU: High Battery Voltage Detected

The system has detected that the electrical charging voltage is exceeding the normal operating range (typically reading 15 volts or higher). As a protective measure, the system may disable powerstages or degrade engine power levels to prevent damage to sensitive electronic components.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL
• 6614
• 6615
• 6616
• 8727
• 8730
• 8732
• 8735
• 8737

1. 1

   Test battery voltage with a multimeter while the tractor engine is running at a high idle (normal is 13.5V - 14.5V; 14.7V or higher indicates overcharging)

2. 2

   Inspect the alternator wiring connections, specifically looking for a corroded, loose, or broken voltage sense wire or a bad ground

3. 3

   Check the battery condition for bulging, excessive heat, or a sulfur smell, which indicates a failing battery with a bad cell

4. 4

   Inspect the alternator for heavy debris (like limestone or field dust) caked inside, which can cause the internal voltage regulator or brushes to malfunction

1. 1

   Disconnect Power

   Disconnect the negative battery cable for safety.

2. 2

   Clean Connections

   Clean all battery terminals, cable ends, and alternator connections. Reconnect and retest the voltage. If the voltage normalizes, the issue was high resistance in the wiring.

3. 3

   Repair Wiring

   If the sense wire or ground wire is corroded or damaged, repair the wiring harness and retest.

4. 4

   Replace Alternator

   If the wiring is intact and the battery is in good condition but the system is still overcharging, the alternator's internal voltage regulator has failed. Because the regulator is internal on these models, the alternator must be replaced.

5. 5

   Removal

   Relieve the drive belt tension and remove the serpentine belt from the alternator pulley. Disconnect the electrical connectors from the rear of the alternator, then unbolt and remove the faulty unit.

6. 6

   Installation

   Install the new alternator, secure the mounting bolts, and reconnect the electrical connections. Reinstall the drive belt and ensure proper tension.

7. 7

   Verification

   Reconnect the battery, start the tractor, and verify with a multimeter that the charging voltage is now within the normal 13.5V - 14.5V range. Clear the fault code using a diagnostic tool if it does not clear automatically.