Case IH 117 – Transmission Controller (TCU): 5F clutch solenoid is shorted to +12 Volts, current sensed while driver is off

The transmission controller continuously monitors the current draw of the 5F clutch solenoid circuit. If the controller detects current flowing to the 5F solenoid when the driver circuit is commanded off, it indicates that the circuit is shorted to a +12V power source. This code will typically trigger whenever the transmission is shifted into forward gears 1, 2, 3, 4, 5, 7, 9, or 11, or during a transmission valve calibration.

• STX Steiger
• Steiger / STX Series (STX325, STX375, STX425, STX440, STX500, Steiger 385-620)
• Magnum Series
• Puma Series
• Maxxum Series

1. 1

   Locate the transmission controller (typically located underneath the fuse/relay panel in the cab). Inspect the wiring harness running from the TCU to the transmission control valve block. Look for chafed wires, melted insulation, or pinched harnesses that could expose the 5F signal wire to a 12V power source.

2. 2

   Disconnect the harness at the 5F clutch solenoid and at the transmission controller. Inspect the pins for corrosion, moisture, or bent terminals that could cause a bridge to a power pin.

3. 3

   With both ends disconnected and the key ON, use a multimeter to measure voltage on the 5F solenoid signal wire. If you read +12 Volts, the wiring harness is shorted to power and must be repaired or replaced.

4. 4

   Measure the resistance across the pins of the 5F clutch solenoid coil. If the resistance is out of specification (shorted internally), the solenoid coil is the culprit. Note: If the problem is temperature-sensitive, the solenoid coil may be starting to fail as it heats up during operation.

5. 5

   If the wiring harness and the solenoid coil both test good, the internal driver inside the transmission controller has likely failed and is bleeding voltage.

1. 1

   Disconnect Power

   Turn off the battery disconnect switch to ensure no power is flowing through the system.

2. 2

   Repair Wiring

   If a short to power was found in the harness, locate the chafed section, splice in a new section of wire using weather-sealed connectors, and re-loom the harness securely away from heat sources or sharp frame edges.

3. 3

   Replace Solenoid

   Clean the area around the transmission control valve block to prevent dirt from entering the hydraulic system. Disconnect the electrical connector from the 5F solenoid. Unbolt and remove the faulty 5F solenoid/coil assembly. Lubricate the O-rings on the new solenoid with clean hydraulic fluid. Install the new solenoid and torque to OEM specifications. Reconnect the electrical harness.

4. 4

   Replace TCU

   If the controller is diagnosed as failed, remove the paneling to access the TCU, swap the module, and use the Case IH Electronic Service Tool (EST) to program the new controller to the tractor.

5. 5

   Calibration

   After any transmission repair, clear the fault codes and perform a transmission valve calibration procedure (often accessed by holding the PROG/DECR keys on the display and following the prompts to calibrate the clutches).