John Deere 2378.06 – CLC: High Current in the Tail Lights Circuit

The control unit has detected that the electrical current draw on the left or right tail light circuit—which also feeds the wide vehicle warning lights and the front/rear trailer sockets—exceeds the nominal capacity of the circuit's fuse (typically 7 Amps).

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7630
• 7730
• 7830
• 7930
• 8130
• 8230
• 8330
• 8430
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630
• 744K
• 770G
• 770GP
• 772G
• 772GP

1. 1

   Isolate the Trailer Circuit: Unplug the 7-pin trailer connector from the front and rear sockets. Restart the tractor to verify if the code still exists. If it clears, the short or overload is in the implement/trailer wiring.

2. 2

   Inspect the Bulbs: Visually check the condition of all tail light and wide vehicle warning light bulbs for blown filaments shorted across internal posts or melted bulb bases.

3. 3

   Inspect the Harness: Check the tail light wiring harness and connections for breaks, chafing against the frame, or loose contacts that could be causing a short to ground.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery ground to ensure safety while working on the electrical system.

2. 2

   Remove Custom Accessories

   If any aftermarket flood lights, hazard lights, or custom accessories are spliced into the tail light circuit, remove them. The CLC is highly sensitive to current draw and aftermarket additions easily overload the 7-amp limit.

3. 3

   Replace Faulty Bulbs/Assemblies

   Remove the tail light lenses and replace any defective or internally shorted bulbs. If the socket itself is melted or corroded, the entire tail light assembly must be replaced.

4. 4

   Repair Wiring

   If the bulbs and trailer socket are fine, trace the wiring harness from the CLC to the rear tail lights. Repair any pinched or exposed wires using heat-shrink butt connectors and re-loom the harness.

5. 5

   Clear the Code

   Reconnect the battery. Restart the engine to verify if the active Diagnostic Trouble Code reappears. The CLC will often correct the code automatically by resetting the communication messages once the normal current draw is restored. If the code persists, a John Deere dealer may need to clear the stored code via their Service ADVISOR tool.