John Deere 521538.03 – RLC (Roof Lighting Control Unit): Left Middle Worklight on Front of Roof or Left Xenon (HID) Worklight on Front of Roof, Voltage Too High

The control software has registered an abnormally high voltage at the output circuit for the front-left middle worklight (or the Xenon/HID equivalent). When this error is detected, the control software may limit or completely disable the functionality of the affected worklight to protect the circuit.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7210R
• 7230R
• 7250R
• 7270R
• 7290R
• 7310R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9360R
• 9370R
• 9410R
• 9420R
• 9460R
• 9470R
• 9470RT
• 9510R
• 9520R
• 9520RT
• 9560R
• 9570R
• 9570RT
• 9620R
• 9620RX
• R4030
• R4038
• R4044
• R4045
• R4060
• 6230
• 6330
• 6430
• 6820
• 6920

1. 1

   Inspect the wiring harness and connectors associated with the left middle worklight (or left Xenon HID worklight) for signs of short circuits to power, pinched wires, or damaged insulation.

2. 2

   Test the left middle worklight assembly to ensure it is functioning correctly and drawing the proper current. A failed internal ballast (on HID models) or a shorted bulb can cause voltage/current anomalies.

3. 3

   Ensure the power supply to the worklight is stable and within the specified range. Inspect the RLC module pins for corrosion or bent terminals that could cause a short.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to ensure safety while working on the electrical system.

2. 2

   Access the Roof Lighting

   Safely access the front roof lighting array. Remove the mounting hardware for the left middle worklight assembly.

3. 3

   Repair Wiring

   If the diagnostic checks revealed compromised wiring or loose connections at the plug, repair or replace the affected wiring harness section. Ensure the terminal locks are properly seated.

4. 4

   Replace Faulty Components

   If the wiring is intact but the light fixture failed the diagnostic test, replace the Xenon (HID) worklight assembly or the bulb.

5. 5

   Reassemble and Test

   Reinstall the worklight assembly into its mounting. Reconnect the battery, clear the stored RLC 521538.03 fault code using a diagnostic tool, and test the lighting system to verify the repair.