Case IH FB1 – Transmission Controller (TCU): Low Range Clutch Solenoid Over Voltage

The controller has detected that the low range clutch solenoid circuit is shorted to +12 volts, or that electrical current is being measured on the circuit when the driver/solenoid is commanded 'off'.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Puma 125
• Puma 210
• Magnum Series
• Steiger Series

1. 1

   Check battery voltage to ensure it is within the normal operating range, as voltage irregularities can trigger false solenoid codes.

2. 2

   Perform a solenoid resistance test: Turn the ignition switch OFF, disconnect the low range clutch solenoid connector, and measure the resistance between terminal 1 and terminal 2 (should be 8 to 11 Ohms).

3. 3

   Perform a harness short test: If the solenoid resistance is okay, disconnect the transmission controller (TCU/CCU) connector and check the wiring harness between the controller and the solenoid for a short to positive voltage (+12V).

1. 1

   Safety Prep

   Lower all equipment to the ground, place shift levers in neutral, block the wheels, relieve hydraulic pressure, and disconnect the battery.

2. 2

   Wiring Repair

   If the diagnostic checks revealed a short to +12V in the harness, trace the wire from the TCU to the transmission valve body and repair the chafed or melted wire.

3. 3

   Solenoid Replacement

   If the solenoid failed the resistance test, unbolt the faulty low range clutch solenoid (PMV valve) from the transmission valve body. Clean the mounting surface, ensure the electrical connector is free of corrosion, and install the new solenoid.

4. 4

   Transmission Calibration

   After replacing the solenoid or repairing the wiring, the transmission clutches must be recalibrated. Hold the High and Low range buttons and start the engine. When 'CAL' appears in the transmission display, release the buttons. Set the engine speed to 1200 ERPM (±100) and follow the specific on-screen prompts to cycle through and calibrate the clutch packs.