John Deere 521559.06 – RLC: Rear Side Roof Flood Light Right Current High

The control module has detected an abnormally high electrical current (amperage) draw on the circuit that powers the right rear side roof work light. This typically indicates a short circuit to ground in the wiring harness, an internal short within the light assembly itself (such as a failed bulb or LED driver), or a malfunction within the control module.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9470RT
• 9520RT
• 9570RT

1. 1

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

2. 2

   Disconnect the electrical connector at the right rear side roof flood light. Turn the tractor and work lights on and check active fault codes. If the code changes to a 'Current Low' or 'Open Circuit' code (e.g., 521559.05), the fault is an internal short inside the light assembly.

3. 3

   Inspect the wiring harness running from the Cab Roof Module (RLC) to the light connector for chafed insulation, pinched wires, or exposed copper touching the cab frame (short to ground).

4. 4

   With the battery disconnected, use a multimeter to check for continuity between the light's power supply wire and a known good chassis ground. A reading near zero ohms confirms a short to ground in the harness.

5. 5

   If the wiring harness tests perfectly and the light is disconnected but the RLC still registers a high current fault, verify the Cab Roof Module (RLC) for an internal hardware failure.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the negative battery cable to prevent electrical shock or further module damage.

2. 2

   Access the Component

   Safely access the right rear side of the cab roof.

3. 3

   Replace the Light (If faulty)

   If diagnostic step #2 proved the light was the culprit, unbolt the mounting hardware for the right rear side roof flood light. Install the replacement light assembly and plug in the electrical connector.

4. 4

   Repair the Wiring (If faulty)

   If a short was found in the harness, carefully open the wire loom at the damaged section. Repair the wire using automotive-grade heat-shrink butt connectors to ensure a weather-tight seal. Re-loom and secure the harness away from pinch points.

5. 5

   Replace the RLC (If faulty)

   If the module is failed, access the Cab Roof Module inside the roof canopy. Disconnect its harness connectors, unbolt the module, and install the new unit. (Note: A new RLC module may require software calibration/programming via John Deere Service Advisor).

6. 6

   Reassembly and Testing

   Reconnect the negative battery cable. Turn the key to the ON position, clear the stored fault codes, and turn on the rear work lights to verify the code does not return and the light operates normally.