Case IH P23 – Electronic Management Unit (EMU): 4WD Output Open Circuit

The control module has detected a break or loss of continuity in the electrical circuit responsible for operating the 4-Wheel Drive (4WD) engagement solenoid.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• MX Series
• TG Series
• CVX 170
• CS 150

1. 1

   Check if connector C034 is connected correctly to the 4WD solenoid. If loose, refit it correctly.

2. 2

   Disconnect connector C034 from the 4WD solenoid. Using a multi-meter, check the resistance across the solenoid terminals. If the multi-meter indicates an open circuit (infinite resistance), the solenoid itself has failed internally.

3. 3

   Check the wiring at C034. Test for continuity between the C034 connector (pin RM57M–B) and the chassis ground. If an open circuit is indicated, trace and repair the fault in the ground circuit.

4. 4

   Disconnect the Electronic Management Unit Connector (C105). Check the wiring harness for an open circuit between the EMU and the solenoid connector.

5. 5

   Check and clean all connectors in the circuit to ensure corrosion is not causing a false open circuit reading.

1. 1

   Secure Connections

   If the diagnostic checks reveal a loose connector at C034 or C105, clean the pins with contact cleaner, apply dielectric grease, and securely reconnect them.

2. 2

   Repair Wiring

   If a break is found in the harness between the EMU and the solenoid, or on the ground side, splice and repair the damaged wire, or replace the affected harness section.

3. 3

   Replace Solenoid

   If the 4WD solenoid fails the multi-meter continuity test, remove the faulty solenoid from the valve block and install a new OEM replacement.

4. 4

   Recalibrate

   If a PWM solenoid valve or the microprocessor is replaced, a Transmission/EDC Calibration procedure must be performed to reset the non-volatile memory in the controller.

5. 5

   Clear Codes

   Cycle the key and clear the stored fault codes to verify the repair.