John Deere 521555.06 – RLC: Front Roof Warning (NA Only) or Front Corner Roof Light (Eur Only) Right Current High

The control module has detected an abnormally high electrical current (amperage draw) on the circuit supplying power to the right-side front roof warning light (on North American models) or the front corner roof light (on European models). This typically indicates a short circuit to ground, a failed light assembly drawing excessive power, or a wiring harness issue.

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

1. 1

   Visually inspect the right front roof warning/corner light assembly for physical damage, cracked lenses, or water intrusion, which commonly causes internal shorting.

2. 2

   Perform a disconnect test: Disconnect the wiring harness connector at the right front roof light. Turn the machine on and check active fault codes. If the code changes to 521555.05 (Current Low), the short is internal to the light. If 521555.06 remains, the short is in the harness or RLC.

3. 3

   Trace the wiring harness from the light back to the Cab Roof Module (RLC). Look for pinched wires, chafed insulation rubbing against the cab frame, or melted wires.

4. 4

   Perform pin testing: Use a multimeter to check for continuity to ground on the power supply pin of the light's harness connector (with the RLC disconnected). Continuity to ground indicates a shorted harness.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Components

   Safely access the cab roof. Depending on the model, you may need to remove the roof cap or access panels to reach the RLC and the routing for the corner lights.

3. 3

   Replace the Light Assembly (If Faulty)

   If the disconnect test proved the light was internally shorted, unbolt the right front warning/corner light, disconnect the pigtail, and install the replacement unit.

4. 4

   Repair the Wiring (If Faulty)

   If a short was found in the harness, cut out the damaged section of wire. Splice in a new section of automotive-grade wire using heat-shrink butt connectors to ensure a weather-tight seal. Secure the harness with zip ties away from sharp metal edges.

5. 5

   Replace the RLC (If Faulty)

   If the wiring tests perfectly and the light is not the issue, the RLC module has failed internally. Disconnect the multi-pin connectors from the RLC, unbolt it from the roof structure, and install the new module. (Note: A new RLC may require software calibration/programming via John Deere Service ADVISOR).

6. 6

   Reassembly and Testing

   Reconnect the battery, turn the key to the ON position, and clear the stored fault codes. Turn on the work lights/warning lights to verify the right front roof light illuminates properly and the 521555.06 code does not return.