John Deere 000168.03 – SSU / SCU / SCO / ACU: Batteries and Alternator Fault

The fault code indicates a problem with the unswitched power supply voltage, meaning the electrical system voltage is either too high or too low. A control module has detected that its power supply is outside the normal operational range, pointing to an underlying issue with the batteries or alternator failing to maintain the correct vehicle voltage.

• 9230
• 9330
• 9430
• 9530
• 9630
• 9430T
• 9530T
• 9630T
• 8230T
• 8330T
• 8430T
• 7630
• 7720
• 7730
• 7820
• 7830
• 7920
• 7930
• 6000 Series
• 7000 Series
• 8000 Series
• 9000 Series
• 4730
• 4830
• 4930
• 4940

1. 1

   Restart the vehicle to see if the fault is a temporary communication glitch

2. 2

   Visually inspect batteries, terminals, and alternator for loose or corroded connections, physical damage, dirt/debris accumulation, and frayed wires

3. 3

   Check relevant control module fuses (F23 for SSU, F29 and F30 for SCU/SCO)

4. 4

   Perform a battery voltage test with the engine off (should be approx 12.6V) and engine running at 1500 RPM (should be 13.5-14.5V)

5. 5

   Perform an alternator ripple test by measuring AC voltage at the alternator output post with the engine running (should be under 0.5V)

1. 1

   Clean and tighten connections

   Clean any corrosion from battery terminals using a wire brush, ensure all cable connections are tight, and remove any debris from around the alternator and batteries.

2. 2

   Replace blown fuses

   If any of the relevant fuses (F23, F29, F30) are blown, replace them with fuses of the correct amperage rating. If a new fuse blows immediately, investigate the wiring for a short circuit.

3. 3

   Charge or replace battery

   If the battery fails a load test or will not hold a charge, it must be replaced.

4. 4

   Check alternator belt

   Ensure the alternator drive belt is in good condition and properly tensioned. A loose or worn belt can slip and prevent the alternator from charging effectively.

5. 5

   Replace alternator

   If diagnostic tests indicate the alternator is faulty (e.g., fails the voltage test or the AC ripple test reads above 0.5V), replace the alternator assembly.

6. 6

   Consult a dealer

   If the fault code persists after these checks, it may indicate a more complex issue within a control module or the wiring harness requiring dealer service.