Case IH 56045 – Transmission Controller (TRANS): 1R Valve Coil Circuit Is Open Or Shorted to Ground When Valve is Off

The transmission controller has turned off the 1st Reverse (1R) clutch solenoid coil, but the voltage sensed on the low side of the coil is lower than expected.

• STX Steiger
• Case IH Puma series
• Case IH Steiger and STX series (e.g., STX-275, 380, 430, 500, 535)
• Case IH CS series (e.g., CS 150)
• Case IH Maxxum and Magnum series

1. 1

   Check the 1R Solenoid Coil for an internal open circuit by measuring its resistance.

2. 2

   Inspect the wiring harness between the 1R clutch solenoid and the transmission controller for an open circuit or a wire shorted to ground.

3. 3

   Verify that power is available from the neutral latch relay, as an open circuit in the solenoid power wire will cause this fault.

4. 4

   Test the transmission controller to see if it has a failed 1R valve coil driver (only if coil, wiring, and power supply test good).

1. 1

   Access the Transmission Valve Block

   Locate the transmission control valve assembly (often located on the side of the transmission or inside the bell housing depending on the specific tractor model).

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short to ground or a broken wire between the TRANS controller and the 1R solenoid, repair or replace the damaged section of the wiring harness.

3. 3

   Restore Power

   If no power is reaching the solenoid, repair the open circuit in the power wire or replace a faulty neutral latch relay.

4. 4

   Replace the 1R Solenoid Valve

   If the 1R solenoid coil tests open (infinite resistance), remove the retaining hardware, extract the faulty 1R solenoid valve, and install a new OEM replacement.

5. 5

   Replace the Transmission Controller

   If all external circuits and the solenoid are perfectly functional, the transmission controller has failed internally and must be replaced and reprogrammed.

6. 6

   Clear Codes and Test

   After repairs, clear the fault codes from the TRANS module and operate the tractor in 1st Reverse to verify the repair.