Case IH 31 – Auxiliary Remote Valve ECU, Transmission TCU, Autopilot Controller, or Instrumentation Controller (ICU2): No unswitched power to the controller / Multiple System Faults

Depending on the system, Fault Code 31 indicates Auxiliary Remote Valve under 8 volts, Transmission Reverse Synchronizer Solenoid Coil Short Circuit, Gyro Y Undervoltage, or Chassis Harness Disconnected. The specific symptom of 'No unswitched power to the controller' indicates the Instrumentation Controller (ICU2) is not powered due to a failed controller power relay, a failed wire to fuse 30/37, or a poor ground supply.

• MX Maxxum
• TN Series Tractors
• MXM / TM Series Tractors
• Steiger / STX Series (STX 325, STX 500)
• Magnum Series (MX255, MX285)

1. 1

   Listen for the cab power relay and controller relay to make a clicking sound when the key is turned to the start/run position

2. 2

   Check fuse 37 and fuse 30 with the key switch on and the display not illuminated

3. 3

   Check for relay coil power at pin 85 (or ring terminal 241) at the controller relay in the fuse compartment behind the operator seat

4. 4

   Check connector C61-40 (or CN2, pin 2) at the instrumentation controller for 12 volts

5. 5

   Check the ground supply at pin C61-39 (or CN2, pin 4)

1. 1

   Replace fuse

   If a fuse is blown, replace it. If the fuse fails immediately upon replacement, trace the circuit for a short to ground.

2. 2

   Replace relay

   If the controller relay receives power at the coil but does not click/operate, replace the relay.

3. 3

   Repair or replace wire

   If there is no power at the relay coil, locate and repair/replace the failed wire between the controller relay and fuse 30.

4. 4

   Replace wire

   If there is no 12V power at the instrumentation controller connector, replace the wire between the fuse block and the controller at pin C61-40.

5. 5

   Clean and correct ground

   If the ground supply is poor, clean the chassis ground connections and correct the grounding problem.

6. 6

   Replace Instrumentation Controller

   If power (12V) and ground are verified at the connector but the controller remains unpowered, replace the Instrumentation Controller.