Case IH 2423 – Transmission Control Unit (TCU) / Transmission Processor: Proper ratio not detected

Correct ratio is not detected because the output speed is too low for the gear selected. The transmission is likely slipping, failing to engage the commanded gear, or suffering from a hydraulic pressure loss, causing a mismatch between the expected and actual output shaft speed.

• Puma/Mid Range Magnum
• Case IH MXM series

1. 1

   Inspect connectors C027 and C028 (which route to clutches A & B) to ensure they are correctly fitted and not loose.

2. 2

   Perform a hydraulic pressure check on the transmission clutches (target pressure is 16 bar).

3. 3

   Verify the transmission synchro potentiometers, as these sensors report the physical gear positions back to the ECU.

1. 1

   Check Connectors

   If connectors C027 and C028 are loose or improperly seated, refit the connectors correctly. Clear the code and test the tractor.

2. 2

   Evaluate Pressure

   If the connectors are fine, the issue is likely a slipping clutch. Hook up a pressure gauge to the clutch test ports.

3. 3

   Address Low Pressure (< 16 bar)

   If the clutch pressure is below 16 bar, the system is losing hydraulic pressure. Inspect and replace the hydraulic PWM (Pulse Width Modulation) valve. If the valve is functioning, trace the system for piston seal leakage or other internal hydraulic leaks.

4. 4

   Address Normal Pressure (= 16 bar)

   If the pressure is at the correct 16 bar but the code persists, the clutch discs themselves are worn out and slipping mechanically. Dismantle the transmission, inspect the clutch packs, and replace the worn clutch discs.