John Deere 2372.03 – CLC / RCU: Brake Lights Circuit Voltage High

The controller has detected that the voltage in the brake light circuit (which often includes the trailer socket brake light feed) is above normal or shorted to a high power source.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9470RT
• 9520RT
• 9570RT
• CH570
• CH670

1. 1

   Cycle power using the key switch or CommandCenter to see if the code clears

2. 2

   Visually inspect brake light bulbs and the trailer socket for internal shorts, corrosion, or debris bridging the contacts

3. 3

   Inspect the wiring harness from the rear chassis/trailer socket to the CLC or RCU for chafing, pinched wires, or melted insulation

4. 4

   Perform a disconnect test by unplugging the trailer socket and rear brake light housings to see if the code becomes inactive or changes to Current Low (002372.05)

1. 1

   Isolate the Short

   Turn off the machine and disconnect the battery. Disconnect the main harness at the rear trailer socket and the brake light assemblies.

2. 2

   Test the Circuit

   Reconnect the battery and turn the key to the ON position. Use a multimeter to check for voltage on the brake light circuit pins at the disconnected ends without the brakes applied. If voltage is present, there is a short to power in the harness.

3. 3

   Repair Wiring

   Trace the harness back toward the Cab Load Center (CLC) or Rear Control Unit (RCU). Locate the area where the brake light wire is shorting to a constant or switched power wire. Repair the damaged wiring using OEM-approved heat-shrink butt connectors and re-loom the harness.

4. 4

   Replace Damaged Receptacles

   If the wiring tests fine, inspect the trailer socket. Replace the socket if internal bridging or corrosion is found.

5. 5

   Clear Codes

   Reconnect all components, turn the key switch on, and verify the brake lights function normally. Clear the stored codes via the CommandCenter™ display.