John Deere 521541.03 – RLC: Rear Side Roof Flood Light Left Voltage High

The controller has detected that the voltage on the circuit supplying the left-side rear roof work light is exceeding the expected normal operating range. This typically indicates a short to power in the wiring harness, a faulty light assembly, or an internal fault within the control module.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 9470RT
• 9520RT
• 9570RT
• 8245R through 8400R

1. 1

   Inspect the left rear side roof flood light assembly for physical damage, water intrusion, or melted plastic.

2. 2

   Disconnect the harness at the left rear roof work light. Check the pins for corrosion, moisture, or pushed-back terminals. Do the same at the RLC module connectors.

3. 3

   With the machine off and the light disconnected, use a multimeter to check for continuity between the light's power supply wire and other power sources to test for a short to power.

4. 4

   Temporarily swap the left rear roof flood light with the right rear roof flood light. If the fault code changes to the right side, the light assembly is internally shorted; if it remains on the left side, the issue is in the harness or the RLC module.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes during repair.

2. 2

   Access the Component

   Safely access the cab roof. Remove the retaining screws or bezel holding the left rear side-facing work light in place.

3. 3

   Repair Wiring (If Applicable)

   If a short to power was found in the harness during diagnostics, locate the chafed or melted section of the wire. Splice and solder a new section of wire, sealing it with dual-wall heat shrink tubing.

4. 4

   Replace the Light Assembly (If Applicable)

   If the light assembly failed the swap test, plug the new OEM work light into the harness and mount it back into the roof housing.

5. 5

   Replace the RLC Module (Worst Case)

   If the harness and light are perfectly fine but the RLC is outputting constant high voltage, the RLC module itself must be replaced. Access the RLC (usually located under the inner cab roof liner), disconnect the multi-pin connectors, and install the new module. Note: A new RLC may require software flashing/configuration via John Deere Service Advisor.

6. 6

   Reassembly and Clearing Codes

   Reconnect the battery. Turn the key to the ON position, clear the stored RLC fault codes via the cab monitor, and turn on the work lights to verify the repair.