Case IH PC4 – Transmission / EDC (Electronic Draft Control) Controller: Engine Torque/RPM Sensor Open Circuit

The Engine Torque/RPM sensor measures engine speed and torque by monitoring the deflection of the flywheel damper spring. An "open circuit" means the control module is not receiving a valid signal from this sensor, typically due to a broken wire, a disconnected plug, or an internal failure of the sensor itself.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• TM115
• TM120
• TM125
• TM130
• TM135
• TM140
• TM150
• TM155
• TM160
• TM175
• TM190

1. 1

   Turn the Power OFF and the Keyswitch OFF

2. 2

   Disconnect the connectors at both ends of the sensor circuit to prevent false readings

3. 3

   Set a multimeter to measure resistance (Ohms)

4. 4

   Check for a short to ground: Use the black meter lead to make contact with a clean, plated metal part on the chassis and the red meter lead to touch the connector pins one at a time (avoid contact with the metal case of the connectors)

5. 5

   Check for continuity across the harness to rule out a broken wire

6. 6

   Rule out failure modes in this order: 1) Faulty connector, 2) Faulty engine torque/RPM sensor, 3) Faulty harness

1. 1

   Inspect the Wiring

   Visually inspect the wiring harness between the Transmission/EDC controller and the Engine Torque/RPM sensor. Look for chafed wires, corrosion, or backed-out pins in the connectors.

2. 2

   Replace the Sensor

   If the harness and connectors test good for continuity and show no shorts to ground, the sensor itself has failed internally and must be replaced. Remove the old sensor from the flywheel housing and install the new unit.

3. 3

   Recalibrate the Transmission

   OEM procedures state that a Transmission/EDC Calibration is required whenever a mechanical repair is effected, a potentiometer/sensor is replaced, or if the shift quality has deteriorated.

4. 4

   Calibration Steps (General MXM/TM Procedure)

   Ensure transmission oil temperature is between 20°C and 50°C. Apply the parking brake, turn off the A/C, and deselect all electrical/hydraulic services. Start the engine. Press and hold the High and Low range buttons until ''CAL'' appears in the transmission display. Set engine speed to 1200 ERPM. Follow the on-screen prompts to calibrate the clutches until the display reads ''END'' or ''CF'' (Calibration procedure completed successfully).