Case IH 6002 – TCU: Rear Diff Lock solenoid has failed

The system flags this code when it detects an electrical fault in the circuit controlling the rear differential lock. Possible failure modes include a failed solenoid coil, damaged wiring, a loose connector or bent pin, or a TCU internal failure.

• Magnum
• Steiger T4B
• Case IH Magnum 235 - 340 (Series 4)
• Case IH MX Magnum Series
• Case IH Puma Series
• Case IH STX / Steiger Series

1. 1

   Visually inspect the rear diff lock solenoid connector (C234) and the TCU connector to ensure they are fully seated, undamaged, and have no bent pins.

2. 2

   Disconnect connector C234 and measure resistance between the solenoid terminals (should be approximately 10 Ohms at 20°C/68°F).

3. 3

   Disconnect the TCU connector and check for continuity between connector C234 pin 1 and the corresponding TCU pin to test for an open circuit.

4. 4

   Check between connector C234 pin 1 and a known good chassis ground to test for a short to ground.

5. 5

   Check between harness end connector C234 pin 1 and connector C234 pin 2 to test for a short circuit.

1. 1

   Resolve Wiring Issues

   If the diagnostic checks reveal an open circuit, short to ground, or short circuit, repair or replace the affected section of the wiring harness.

2. 2

   Replace the Solenoid

   If the solenoid fails the 10-Ohm resistance test, remove the faulty rear diff lock solenoid from the valve block and install a new one.

3. 3

   Software/TCU Replacement

   If the harness and solenoid both test perfectly fine, download/flash the correct level of software to the TCU. If the fault re-occurs after the software update, the TCU has suffered an internal failure and must be replaced.

4. 4

   Clear and Verify

   Once the physical repair is complete, clear the error code from the system and test the tractor to ensure normal operation of the rear differential lock.