John Deere 3598.04 – OIC, VCU, SIC, or VLC: Supply Voltage #2 for Control Unit Too Low / 5 Volt Sensor Supply 2 Short to Ground

The definition depends on the control module logging the fault. OIC indicates the cab control unit is receiving insufficient voltage on its secondary power circuit. VCU indicates a short to ground on the 5-volt reference circuit powering specific sensors. SIC indicates a potential short to ground on the relay powered by the SIC output. VLC indicates Wake Up Signal Voltage Low.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC
• 318E
• 319E
• 320E
• 323E
• 326E
• 331G
• 333G
• 6230
• 6330
• 6430
• 8245R
• 8400R

1. 1

   [If OIC] Check System Voltage: Verify the tractor's batteries are fully charged and the alternator is outputting proper voltage (approx. 13.5V - 14.2V).

2. 2

   [If OIC] Inspect Fuses: Check the Cab Load Center (CLC) for blown fuses related to the OIC unswitched and switched power supplies.

3. 3

   [If OIC] Test Harness Voltage: Disconnect the OIC harness and use a multimeter to test the 12V supply pins. If voltage is low at the connector but good at the fuse panel, there is high resistance or a partial short in the wiring harness.

4. 4

   [If OIC] Check Grounds: Verify the cab ground straps and OIC ground pins are clean and tight.

5. 5

   [If VCU] Disconnect sensors on the 'Supply 2' 5-volt reference circuit one at a time. If the 5V reference returns to normal after unplugging a specific sensor, that sensor is internally shorted.

6. 6

   [If VCU] If unplugging sensors does not restore the 5V supply, inspect the wiring harness for chafing or pinching against the machine frame (short to ground).

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery cable.

2. 2

   Access the OIC

   Remove the necessary interior cab trim panels to access the Operator Interface Control Unit (usually located in the right-hand console or armrest).

3. 3

   Repair Wiring

   If the diagnostic checks revealed a voltage drop between the fuse panel and the OIC, trace the specific power supply wire. Cut out any corroded sections or damaged pins and splice in new wiring using weather-sealed connectors.

4. 4

   Clean Contacts

   Spray the OIC connectors with electronic contact cleaner and apply dielectric grease to prevent future moisture intrusion.

5. 5

   Reassemble and Clear Codes

   Reconnect the battery, turn the key to the ON position, and use the CommandCenter display or Service ADVISOR tool to clear the stored 003598.04 code. Cycle the key to verify the code does not return.