John Deere 2350.03 – BLC / VLC / VCU: Low Beam Light Circuit Fault - Voltage High

The control module is detecting voltage on the low beam headlight circuit pin when the headlights are commanded OFF, indicating a short to power, a voltage backfeed in the wiring loom, or an internal failure within the module itself keeping the circuit energized.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC
• 8R Series (8245R to 8400R)
• 250D
• 300D
• 260E
• 310E
• 770G
• 770GP
• 772G
• 772GP
• 310SK
• 315SK
• 524K
• 544K
• 624K
• 944K

1. 1

   Verify the symptom: Check if the low beam headlights remain illuminated when the cab switch is turned off.

2. 2

   Disconnect the headlight command switch in the cab. If the voltage drops and the lights turn off, the switch is internally shorted and sending a false 'ON' command.

3. 3

   Disconnect the low beam headlights and use a multimeter to check for voltage at the harness connectors. If voltage is present with the switch off, there is a short to power.

4. 4

   Disconnect the main harness from the BLC/VLC/VCU and check the module's output pin for the low beam circuit. If the module is outputting 12V/24V while the harness is disconnected and the switch is off, the module's internal driver has failed closed.

5. 5

   Inspect the module connectors for water ingress, corrosion, or bent pins that could be bridging a constant power wire to the low beam circuit pin.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent further electrical damage.

2. 2

   Trace the Loom

   If the diagnostic checks point to a wiring issue, visually trace the front lighting wiring loom. Pay close attention to high-friction areas such as hood hinges, the front grille area, and where the harness routes into the cab frame.

3. 3

   Repair Wiring

   If a chafed or melted wire is found shorting the low beam circuit to a constant battery power wire, cut out the damaged section. Splice in new wire using OEM-approved heat-shrink butt connectors to ensure a weather-tight seal.

4. 4

   Replace Module (If Applicable)

   If the wiring loom tests perfectly fine and the switch is not the culprit, the BLC (or VLC/VCU) has an internal short. Remove the mounting hardware, disconnect the remaining harness plugs, and install a replacement module. (Note: A new module may require software flashing/calibration via John Deere Service ADVISOR).

5. 5

   Test and Clear

   Reconnect the battery. Turn the key to the ON position and test the headlight switch operation. Connect a diagnostic tool to clear the 002350.03 fault code from the module's memory.