John Deere 000444.03 – RLC: RLC Unswitched Supply Voltage High

The Roof Lighting Control (RLC) module has detected that the voltage in its constant (unswitched) power supply circuit exceeds the normal operating range, specifically rising above 16 volts. This high voltage condition typically points to a charging system overvoltage or a wiring issue affecting the module's power supply.

• 9470RT
• 9520RT
• 9570RT
• 6R Series

1. 1

   Check the vehicle charging system by measuring voltage at the battery with the engine running (normal is typically 13.5-14.8 volts; consistently higher indicates an alternator issue)

2. 2

   Inspect the wiring harness and connections leading to the Cab Roof Module (RLC), paying close attention to main power and ground connections for corrosion, damage, or loose pins

3. 3

   Reduce the electrical load on the tractor to determine if the voltage returns to a normal range

4. 4

   Cycle the tractor's main power by turning the key switch off and on to see if the temporary fault resets

1. 1

   Verify fault

   Use a diagnostic scanner to confirm that RLC 000444.03 is an active fault.

2. 2

   Test and repair charging system

   If the charging system voltage is excessively high (over 14.8V), replace the alternator or voltage regulator.

3. 3

   Repair wiring

   If the charging system is functioning correctly, repair any identified issues in the wiring harness or connectors for the RLC module. Ensure all connections are clean and secure.

4. 4

   Isolate and diagnose module

   If no issues are found with the charging system or wiring, consult a qualified technician to perform advanced diagnostics on the RLC module itself.

5. 5

   Replace RLC module

   If the RLC module is determined to be faulty, replace it. Note that the new module may require programming or calibration by a dealer.