Massey Ferguson 168.01 – Engine Control Unit (ECU): Battery Voltage Low (ECU) / Unswitched Battery Voltage Extremely Low

The power supply voltage to the control unit has dropped below the normal operating range (typically < 6.5 V or < 7.8 V).

• 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
• 9695
• 9795

1. 1

   Battery Voltage Test: Measure the static battery voltage at the battery posts.

2. 2

   Alternator Output Test: Start the engine and measure the voltage to ensure the alternator is charging the system properly.

3. 3

   Connection Inspection: Inspect the battery terminals, ground cables, and the battery disconnect switch for corrosion, looseness, or damage.

4. 4

   Wiring Harness Check: Inspect the wiring harness supplying power to the Engine ECU. Look for chafed wires, poor pin connections, or voltage drops between the battery and the ECU connector.

1. 1

   Clean Connections

   If corrosion is found, disconnect the battery cables (negative first) and clean the battery posts and terminals. Reconnect and tighten securely.

2. 2

   Replace the Battery

   If the battery fails a load test or cannot maintain a charge above the required threshold, remove the battery hold-down bracket, disconnect the cables, and install a new battery.

3. 3

   Replace the Alternator

   If the alternator is failing to charge the battery while the engine is running, disconnect the battery, remove the serpentine/V-belt, disconnect the alternator electrical connections, unbolt the alternator, and install a replacement unit.

4. 4

   Repair Wiring/Switches

   If the battery and alternator test fine but voltage at the ECU is still low, repair any damaged sections of the wiring harness or replace a faulty battery cut-off switch.

5. 5

   Clear Codes

   Turn the ignition off for a minimum of 60 seconds to allow a system reset, then turn it back on and use a diagnostic service tool to clear the fault code.