Case IH 7020 (746.03) - DEC – Transmission Control Unit (TCU) or PTO Controller: DiffLock Solenoid - LSD short to high voltage

The control module is detecting voltage on the solenoid's circuit that is higher than the expected operating range, typically indicating a short circuit to the battery voltage (VCC).

• VESTRUM CVX
• 3220
• 3230
• 4210
• 4230
• 4240
• 5120
• 5130
• 5140
• 5220
• 5230
• 5240
• MX210
• MX230
• MX255
• MX285
• Puma 165-225
• 580L
• 580M
• 580N
• 590 Super L
• 590 Super M
• 590 Super N
• 570LXT
• 585G
• 586G

1. 1

   Remove the controller cover from the rear of the tractor to access the controller.

2. 2

   Disconnect the specific connector (e.g., connector C057 - black) from the controller.

3. 3

   Inspect the pins in the connector for damage or corrosion. Clean the mating pins and the connector.

4. 4

   Check the wiring harness for any areas where the cable might be defective and contacting battery voltage.

5. 5

   Test the continuity of the wiring from the controller to the solenoid (e.g., between pin 9 and chassis ground).

6. 6

   Test the resistance of the DiffLock solenoid. A healthy solenoid should measure approximately 8.5 - 9.7 ohms.

1. 1

   Trace wiring harness

   Trace the wiring harness from the ECU/TCU to the DiffLock solenoid to locate and repair any wires shorting to a power source.

2. 2

   Replace solenoid

   If the wiring is intact and the resistance test (8.5 - 9.7 ohms) fails, the solenoid has an internal defect and must be replaced.

3. 3

   Swap solenoids

   On some models (like the 5140), temporarily swap the difflock solenoid with the modulation solenoid (located one above the other) to see if the fault follows the solenoid.