John Deere 521565.03 – CLC (Cab Load Controller): Trailer Work Light Circuit Voltage High

The circuit is shorted to a power source, indicating a 'Voltage High' condition.

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

1. 1

   Inspect the wiring harness leading to the trailer work light / right rear mud guard work light for chafing, pinched wires, or exposed copper that could be shorting directly to a 12V power source.

2. 2

   Locate the work light relay in the fuse/relay panel and test it to ensure the internal contacts are not stuck closed (which would constantly send high voltage to the circuit).

3. 3

   Disconnect the work light and the CLC connectors. Check for corrosion, water ingress, or bent pins that could bridge power to the light circuit.

4. 4

   With the harness disconnected, use a multimeter to verify if the CLC is outputting the correct voltage when the switch is activated, and dropping to 0V when turned off.

1. 1

   Disconnect Power

   Disconnect the negative battery cable before performing electrical repairs to prevent further module damage.

2. 2

   Isolate the Short

   If a short to power was found in the wiring harness during diagnostics, repair the damaged section of the wire using weather-sealed splice connectors, or replace the affected harness section.

3. 3

   Replace Faulty Components

   If the relay was found to be stuck closed, replace it with a new OEM relay. If the work light assembly itself has an internal short, replace the light housing.

4. 4

   Reconnect and Test

   Reconnect the battery. Turn on the tractor and activate the rear work lights/trailer lights to ensure they function normally without blowing fuses or triggering high voltage.

5. 5

   Clear Codes

   Access the tractor's diagnostic monitor (CommandCenter) and clear the stored CLC 521565.03 fault code.