John Deere 168.04 – CSM / AIC: Unswitched Supply Voltage Low

This error code indicates that the unswitched supply voltage to the specific control module (either the Cab Switch Module or the Armrest Interface Control Unit) has dropped below the normal operational threshold of 9.0 volts. When this occurs, the control unit will typically disable its functions or enter a protective safety mode.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7200R
• 7215R
• 7230R
• 7260R
• 7280R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8345R
• 8400R
• 9360R
• 9410R
• 9460R
• 9470RT
• 9520RT
• 9570RT
• Self-Propelled Forage Harvesters (SPFH)

1. 1

   Visually inspect the batteries and alternator for signs of damage, corrosion, or accumulated debris.

2. 2

   Test the battery resting voltage (should be ~12.6V) and the alternator charging voltage while running (should be 13.5V - 14.5V).

3. 3

   Inspect the main cab power fuses and unswitched power fuses (e.g., F12, F24, F51, depending on your specific model's fuse block).

4. 4

   Inspect the wiring harness and connectors going to the CSM or AIC for loose pins, chafed wires, or corrosion.

5. 5

   Use a multimeter to measure the voltage directly at the unswitched power input pins on the module's harness. It must be above 9.0V.

1. 1

   Power Down

   Turn off the machine and remove the key.

2. 2

   Clean Power Sources

   Clean the battery terminals and ensure the ground cables attached to the chassis are tight and free of rust/paint.

3. 3

   Trace the Voltage Drop

   If the battery has 12V but the module harness pin shows less than 9.0V, trace the unswitched power wire back to the fuse panel. Look for pinched wires in the cab routing or a failing relay/fuse socket.

4. 4

   Repair Wiring

   Repair any damaged sections of the wiring harness or replace blown fuses.

5. 5

   Module Replacement (If Necessary)

   If the harness delivers a healthy 12V+ to the module, but the module still registers a 168.04 low voltage internal fault and remains disabled, the module's internal power supply circuit has failed. Replace the CSM or AIC module.

6. 6

   Reset and Calibrate

   Reconnect the harness, cycle the key switch to clear the fault code, and test the armrest/cab switch functions. (Note: A new module may require software configuration/calibration via John Deere Service ADVISOR).