John Deere 2386.03 – RLC (Roof Lighting Controller / Cab Roof Module) or CAB (Cab Module): Beacon Light Voltage High / Beacon Light Short to Power

Generated when the control software registers that the voltage at the output to the beacon light is too high, specifically if a voltage higher than 16 volts is detected.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8R Series (8245R to 8400R)
• 8RT Series
• 8RW Series
• 9RT Series (9470RT, 9520RT, 9570RT)
• 250D
• 300D Series II
• 260E
• 310E
• 944K Hybrid 4WD Loader
• 524KII Loader
• STS Series (9470 STS, 9570 STS)

1. 1

   Inspect the beacon light circuit wiring and connectors for signs of a short circuit to power, damaged insulation, pinched wires, or loose connections.

2. 2

   Verify the power supply to the beacon light is stable and under 16 volts, and inspect the alternator output for overcharging issues.

3. 3

   Ensure that the configuration of address RLC 056 is correct in the control software.

4. 4

   Test the beacon light directly to ensure it is functioning correctly and drawing the proper current/voltage without internal shorting.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical shock or further module damage.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short to power in the harness, repair or replace the compromised wiring and connectors.

3. 3

   Replace the Beacon

   If the wiring is intact but the beacon light itself has an internal short causing the voltage fault, remove the mounting bolt/nut from the DIN stem mount or bracket and disconnect the harness.

4. 4

   Install New Beacon

   Mount the replacement beacon light, secure the hardware, and plug in the electrical connector.

5. 5

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a John Deere diagnostic tool (Service ADVISOR) to clear the RLC 002386.03 code. Test the beacon switch to verify the repair.