John Deere 158.01 – RLC: Switched Supply Voltage Low

The control unit detects that the switched battery supply voltage (ELX voltage) has dropped below a critical threshold (typically 12.0V or 12.5V) for more than 2 seconds while the engine is running (above 1500 RPM).

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5M Series
• 7R Series
• 8R Series
• 9R Series

1. 1

   Monitor system voltage using the dash display or a multimeter at the power strip to ensure it remains above 12.0V under all operating conditions.

2. 2

   Check the alternator to verify it is providing adequate charging voltage, and inspect the alternator belt for wear and proper tension.

3. 3

   Inspect the batteries to ensure they are fully charged and look for signs of deterioration, damage, or accumulated debris.

4. 4

   Inspect the main ground wire between the engine and the cab, and check all electrical connections related to the RLC, battery, and alternator for security, cleanliness, and corrosion.

5. 5

   Perform load testing by reducing electrical load (e.g., turning off customized accessories) or increasing engine RPM to see if the system recovers and the code clears.

1. 1

   Cycle Power

   Turn off the tractor, cycle the key switch, and restart the engine to see if the code is an intermittent glitch.

2. 2

   Service the Battery

   If the battery fails a load test or shows low resting voltage, replace the battery and clean the battery terminals.

3. 3

   Service the Alternator

   If the alternator is not outputting sufficient voltage (typically 13.5V - 14.5V while running), replace the alternator and/or the serpentine belt.

4. 4

   Repair Wiring/Grounds

   Clean and tighten the main cab ground post where multiple grounds converge. Repair or replace any frayed or damaged wires in the wiring harness supplying the cab roof.

5. 5

   Clear Codes

   After repairs, run the engine above 1500 RPM to ensure the voltage remains stable and the RLC module receives adequate power. The code should clear or can be cleared via the CommandCenter.