Case IH 14020 – Instrument Cluster or Auxiliary System Controller / Steering System: Vkey line in fault OR Loss of CAN messages sent by the auxiliary system controller steering system

Depending on the tractor series, this code indicates either an abnormal voltage condition on the ignition switch input line (Vkey line in fault) or a communication failure on the CAN bus related to the auxiliary steering system (Loss of CAN messages).

• MAXXUM T4E
• VESTRUM CVX
• Farmall 40
• Farmall 45
• Farmall 50
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Quadtrac 350
• Quadtrac 400
• Quadtrac 450
• Quadtrac 500
• Quadtrac 550
• Quadtrac 600

1. 1

   For Vkey fault: Check battery and base voltage: Ensure the battery is fully charged and the terminals are clean, as low system voltage can trigger false Vkey faults.

2. 2

   For Vkey fault: Inspect fuses and relays: Check the fuse box for any blown fuses or sticking relays that supply switched ignition power to the instrument cluster.

3. 3

   For Vkey fault: Test the ignition switch: Use a multimeter to test the back of the ignition switch. Verify that the Vkey terminal outputs steady battery voltage when the key is turned to the 'ON' position.

4. 4

   For Vkey fault: Test harness continuity: Disconnect the instrument cluster harness and measure the continuity of the Vkey wire from the ignition switch to the cluster to check for open circuits or chafing.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts during repair.

2. 2

   Access the Components

   Remove the steering column cowling and dash panels to access the rear of the ignition switch and the instrument cluster wiring harness.

3. 3

   Repair Wiring

   If the diagnostic checks revealed a broken or chafed wire between the ignition switch and the instrument cluster, cut out the damaged section, solder in a new piece of wire of the same gauge, and seal it with heat shrink tubing.

4. 4

   Replace the Ignition Switch

   If the switch failed the multimeter test (intermittent or no voltage output on the Vkey terminal), unplug the switch connector, remove the retaining nut on the front of the dash, and install a new ignition switch.

5. 5

   Reassemble and Clear Codes

   Reconnect the instrument cluster and dash panels. Reconnect the negative battery cable. Turn the key to the ON position and use an Electronic Service Tool (EST) or the instrument cluster diagnostic menu to clear the inactive fault code.