Massey Ferguson D125 – Dashboard or Instrument Panel / Cluster (Dash): Alternator regulator voltage too high (filtered battery signal)

This indicates an overcharging condition where the alternator's voltage regulator is allowing too much voltage to reach the battery and electrical system (typically anything above 14.7 volts). If left unchecked, this can boil the battery acid, ruin the battery, and damage sensitive electronic components.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 5400 Series
• MF 6400 Series
• MF 7600 Series
• MF 5600 Series
• MF 6600 Series
• MF 6700 Series
• MF 7700 Series
• MF 8700 Series

1. 1

   Check the battery fluid/acid/water level and overall health. A battery with low fluid levels can trick the system into overcharging.

2. 2

   Perform a live voltage test. Start the tractor and measure the voltage at the battery terminals with a multimeter. A reading above 14.7 volts indicates the voltage regulator is failing and overcharging the system.

3. 3

   Perform a ground circuit voltage drop test. Connect a multimeter between the battery's negative terminal and the engine block ground with the key on. A reading higher than 0.1 volts indicates high resistance (a bad ground), which can cause regulator reference issues.

4. 4

   Check the alternator belt for proper tension and condition.

5. 5

   Inspect the alternator wiring harness, specifically looking for a loose 'sense' wire, which can cause the alternator to output maximum voltage because it thinks the battery is dead.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent short circuits.

2. 2

   Remove the Belt

   Relieve tension on the serpentine/drive belt and remove it from the alternator pulley.

3. 3

   Disconnect Wiring

   Unbolt the heavy gauge B+ (battery positive) wire and unplug the electrical connector/sense wires from the rear of the alternator.

4. 4

   Remove Alternator

   Remove the mounting bolts securing the alternator to the engine bracket and lift the unit out.

5. 5

   Install New Alternator

   Position the new alternator, insert and tighten the mounting bolts.

6. 6

   Reconnect

   Reattach the electrical connections and the B+ wire. Route the drive belt back over the pulley and restore proper belt tension.

7. 7

   Verify Repair

   Reconnect the battery, start the tractor, and test the voltage at the battery. It should now read a steady 13.5V to 14.5V. The D125 code on the dash should clear.