John Deere 2378.05 – Cab Load Center (CLC): Lighting System - Tail Light Circuit Current Problem / Low Current in Tail Light Circuit

The control unit detects an open circuit in either the left or right tail light, resulting in abnormally low or no current flow. This open circuit is typically caused by a burned-out light bulb, broken wires, poor electrical connections, or a faulty tail light assembly.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7630
• 7730
• 7830
• 7930
• 7810
• 7210J
• 744K Series II 4WD Loaders

1. 1

   Cycle the power by restarting the engine and cycling the key switch to see if the code clears

2. 2

   Unplug the 7-pin trailer connector (if attached) to verify if the code still exists, ruling out a towed implement fault

3. 3

   Physically check the condition of both the left and right tail light bulbs to see if the filament is broken

1. 1

   Acknowledge the Code

   Press the select switch on the CommandCenter to acknowledge the code and return the display to normal mode.

2. 2

   Replace the Bulb

   If the visual inspection reveals a burned-out bulb, replace it with a new one.

3. 3

   Inspect the Wiring

   If the bulbs are intact, trace the wiring harness leading to the left and right tail light assemblies. Look for broken wires, chafing, or disconnected plugs.

4. 4

   Clean Connections

   Disconnect the tail light harness connectors and inspect for corrosion or moisture intrusion. Clean the contacts and reconnect securely.

5. 5

   Test the Assembly

   If the wiring is intact and the bulbs are good but the code persists, the tail light assembly itself may have an internal open circuit and will need to be replaced.

6. 6

   Clear the Code

   Cycle the tractor power to verify the repair. If the code still exists after these steps, John Deere documentation advises having a dealer perform advanced diagnostics on the CLC module.