Massey Ferguson E168.00 – Engine Control Unit (ECU): Battery Voltage High

The control unit is receiving a voltage signal that exceeds the maximum safe operational limit (> 17.0 V on standard 12V systems or > 36.0 V on 24V heavy-duty systems).

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• MF 8600 Series
• 9695
• 9795

1. 1

   Perform a static battery test with the engine off to verify voltage across the battery terminals is approximately 12.6V.

2. 2

   Perform a charging system test with the engine running to see if voltage climbs above 15.0V and approaches 17.0V (indicating overcharging).

3. 3

   Inspect the wiring harness between the alternator, battery, and ECU for shorts to a higher voltage source or damaged grounds.

4. 4

   Check the battery for signs of boiling, swelling, or acid leaks caused by severe overcharging.

1. 1

   Isolate the Alternator

   If the charging system test confirms voltage is exceeding 17V while the engine is running, the alternator's internal voltage regulator has failed.

2. 2

   Disconnect Power

   Turn off the tractor and disconnect the negative battery cable to prevent electrical shocks or further ECU damage.

3. 3

   Remove the Alternator

   Disconnect the electrical connectors from the rear of the alternator. Release the serpentine belt tensioner, remove the belt from the alternator pulley, and unbolt the alternator from its mounting bracket.

4. 4

   Replace Components

   Install a new alternator assembly (or replace the voltage regulator module on the back of the alternator if it is serviceable separately on your specific model).

5. 5

   Reassemble and Test

   Reinstall the drive belt, reconnect the electrical connections, and reconnect the battery.

6. 6

   Clear Codes

   Start the tractor and verify with a voltmeter that the charging voltage is now stable (typically between 13.8V and 14.4V). Use a diagnostic scan tool or the tractor's dashboard diagnostic menu to clear the E168.00 inactive fault code.