John Deere 000168.01 – ECU / PTQ / XMC: Battery Voltage Below 8V

A control unit on the machine has detected that the system electrical voltage has dropped below a critical operational threshold, often below 9 volts (SPN 168, FMI 1). This low voltage condition can prevent the proper functioning of essential electronic components, including controllers, sensors, and injectors.

• 5M Series
• 6M Series
• 6R Series
• 6105M
• 6110M
• 6115M
• 6125M
• 6155M
• 6195M
• 7000 Series
• 7200
• 7400
• 8000 Series
• 9000 Series
• 7400A TerrainCut
• 7460 Cotton Stripper

1. 1

   Visually inspect the battery terminals for corrosion, which can be cleaned with a solution of baking soda and water.

2. 2

   Check all battery cables and connections for tightness and any signs of wear or damage, ensuring ground connections are clean and secure.

3. 3

   Examine the alternator belt for proper tension and any signs of wear or damage.

4. 4

   Inspect visible wiring for any damage from wear, corrosion, or rodents.

5. 5

   Perform a static battery voltage test with the engine off (should read approximately 12.6 to 12.7 volts or higher; a reading below 10.5V may indicate a dead cell).

6. 6

   Perform a battery voltage test with the engine running at a moderate RPM (around 1500 RPM). The reading across the battery terminals should increase to between 13.5 and 14.5 volts. If it does not increase or drops, it points to a charging system problem.

7. 7

   Perform a battery load test to assess the battery's ability to hold a charge under load.

8. 8

   Perform a hydrometer test (for serviceable batteries) to check the specific gravity of the electrolyte in each cell (1.250 or higher indicates a full charge; variations of 0.030 or more suggest a failing battery).

9. 9

   Perform an alternator output test with the engine running at the alternator's output terminal (B+) (should be between 13.5 and 14.5 volts).

10. 10

    Perform an AC ripple test at the alternator's output post (a reading above 0.5V could indicate faulty alternator diodes).

11. 11

    Perform a voltage drop test between the alternator's output post and the battery's positive terminal while the engine is running with electrical loads on (a drop of more than 0.5 volts indicates excessive resistance in the charging circuit).

12. 12

    Check all relevant fuses and relays for faults, as a blown fuse or bad relay can interrupt the charging circuit.

1. 1

   Safety First

   Park the machine on a level surface, turn off the engine, and engage the park brake. Always wear appropriate personal protective equipment, including eye protection and gloves, when working with batteries. When disconnecting the battery, always remove the negative (-) cable first and reconnect it last.

2. 2

   Clean Connections

   Disconnect the battery cables and thoroughly clean the battery posts and cable terminals using a wire brush and a cleaning solution. Reconnect the cables securely.

3. 3

   Charge the Battery

   If the battery is low but otherwise healthy, fully charge it using an appropriate battery charger.

4. 4

   Re-test

   After charging, repeat the battery voltage and load tests. If the battery fails to hold a charge, it must be replaced.

5. 5

   Test the Alternator

   If the battery is in good condition but the fault persists, perform the alternator output and ripple tests. If the alternator is not producing the correct voltage or shows excessive AC ripple, it is likely faulty and needs to be replaced.

6. 6

   Inspect Wiring and Fuses

   If both the battery and alternator test as good, meticulously inspect all wiring in the charging circuit for damage, loose connections, or corrosion. Check for any parasitic electrical drains that could be discharging the battery when the machine is off. Replace any damaged wires or blown fuses.

7. 7

   Replace Faulty Components

   If the battery is determined to be faulty, replace it with a new one that meets the OEM specifications for your machine model. If the alternator is faulty, replace it.

8. 8

   Final System Check

   After any replacements, start the engine and verify that the charging voltage at the battery is within the normal range (13.5-14.5 volts) to confirm the repair.