Case IH t88 – Transmission Control Module (TCM) / Power Control Unit (PCU): Solenoid Valve Power Stage 2, Data Valid But Below Normal Range

The control module is successfully communicating with the circuit for the transmission's Solenoid Valve Power Stage 2, but the electrical value (voltage or current) returning from the circuit is lower than the expected operating threshold. This typically points to high electrical resistance, a failing solenoid coil, corroded pins, or a partial open circuit in the wiring harness.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Turn the Keyswitch OFF and disconnect the battery to prevent false readings or short circuits.

2. 2

   Disconnect the wiring harness connectors at both the PCU/TCM end and the transmission valve block end to isolate the circuit.

3. 3

   Check the connector pins at the transmission valve block for dirt, moisture, or corrosion, which commonly cause 'below normal range' voltage drops.

4. 4

   Set a multimeter to measure Ohms (resistance) and measure the circuit resistance of the wiring harness to ensure there are no breaks or high-resistance chafing. Use a clean chassis ground.

5. 5

   Measure the resistance across the pins of the Solenoid Valve Power Stage 2 directly. If the resistance is out of specification, it indicates a burnt or failing internal winding.

1. 1

   Prep the Machine

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

2. 2

   Locate the Valve Block

   Locate the transmission control valve block (often the PMV or EDC valve block) on the side of the transmission housing.

3. 3

   Remove the Faulty Solenoid

   Disconnect the electrical connector to the Stage 2 solenoid. Unbolt the solenoid from the valve body.

4. 4

   Clean and Install

   Clean the mounting surface thoroughly to prevent contamination of the hydraulic circuit. Install the new proportional magnetic valve (PMV) solenoid and torque the bolts to spec.

5. 5

   Reconnect

   Reconnect the electrical harness and the battery.

6. 6

   Transmission Calibration

   Hold the High and Low range buttons and start the engine. Wait for 'CAL' to appear on the transmission display, then release the buttons. Set the engine speed to 1200 ERPM and follow the on-screen prompts to cycle through the clutch pack calibrations until complete.