John Deere 2348.03 – VLC or CAB: High Beam Lights Circuit Voltage High

The control module detects voltage on the high beam headlight circuit even though the switch/command is turned off. This is typically caused by a voltage backfeed in the wiring loom (a short to a constant power source), a stuck lighting relay, or an internal failure (shorted driver) within the control module itself.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 8R Series
• 8RW Series
• 8245R
• 8400R
• 9RT Series
• 9470RT
• 9520RT
• 9570RT
• STS Series
• 9470 STS
• 9570 STS
• 9670 STS
• 9770 STS
• 9870 STS
• 770G
• 770GP
• 772G
• 772GP
• 250D
• 300D Series II
• 260E
• 310E
• CH570
• CH670

1. 1

   Inspect the main cab/roof wiring loom and the front headlight harness for chafing, pinched wires, or melted insulation that could cause a short to a constant 12V power wire.

2. 2

   Disconnect the high beam headlights/roof lights and use a multimeter to check for voltage at the connector with the headlight switch turned OFF.

3. 3

   Disconnect the lighting harness directly at the VLC or CAB module and test the high beam pin on the harness side for voltage to identify a wiring loom backfeed.

4. 4

   Test the high beam pin on the module side (with harness disconnected) to see if the module is outputting voltage when commanded off, indicating an internal module failure.

5. 5

   If the machine utilizes external relays for the high beams, test the high beam relay to ensure the contacts are not welded shut.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery terminal before performing electrical repairs.

2. 2

   Harness Repair

   If a backfeed is found, trace the high beam circuit wire through the loom. Locate the short to power, cut out the damaged section of wiring, and splice in a new section using weather-sealed heat-shrink butt connectors. Wrap the repaired loom in protective conduit.

3. 3

   Relay Replacement

   If applicable, pull the faulty high beam relay from the fuse/relay block and replace it with a new OEM relay.

4. 4

   Module Replacement

   If the module is internally shorted, disconnect all harness connectors from the VLC or CAB module, unbolt it from its mounting bracket, install the new module, and reconnect the harnesses. Note: A new module will likely require a payload/software calibration using John Deere Service ADVISOR.

5. 5

   Verify Repair

   Reconnect the battery, turn the key to the ON position, and toggle the high beams on and off to ensure the lights operate correctly and the 002348.03 code changes from Active to Stored. Clear the stored codes.