New Holland MFD 6005 – TCU (Tractor Control Unit / Transmission Controller): Rear Differential Lock and Auto Differential Lock (Only CCH): 1. Diff Lock On and Auto Diff Lock switches are both active.

This code indicates an illogical condition where the system detects that both the manual "Diff Lock On" switch and the "Auto Diff Lock" switch are being pressed or are sending an active signal at the exact same time. Because the system cannot be in manual override and automatic mode simultaneously, it triggers this fault and disables the differential lock system to prevent drivetrain damage.

• T6000
• T7000
• T7
• T8
• Puma
• Magnum (Series 4)
• Steiger

1. 1

   Check the Diff Lock and Auto Diff Lock switches on the armrest. Ensure neither switch is mechanically stuck, jammed by dirt/debris, or physically damaged.

2. 2

   Clear the error code using the tractor's onboard diagnostic menu or an approved diagnostic tool. Cycle the switches manually a few times to free up any sticking contacts, then operate the tractor to see if the code returns.

3. 3

   Use the tractor's onboard H MENU SWITCH & SENSOR TEST FUNCTIONS (specifically the H9 menu) to monitor the live state of the armrest switches. Verify if the system is constantly seeing a closed circuit for both switches without you pressing them.

4. 4

   Inspect the wiring harness connecting the armrest controller to the TCU. Look for chafed wires that could be causing a short circuit between the manual and auto switch signal wires.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent electrical shorts during disassembly.

2. 2

   Access the Armrest Module

   Remove the armrest console cover to access the underside of the Custom Control Handle / switch panel.

3. 3

   Test the Switches

   Disconnect the switch module connector. Using a digital multimeter, test the continuity of the Diff Lock switch and the Auto Diff Lock switch. If either switch shows continuity (a closed circuit) when not being pressed, the switch has failed internally.

4. 4

   Test the Harness

   If the switches test fine, check the harness for a short to voltage or a short between the two switch signal wires leading back to the Armrest Controller Module.

5. 5

   Replace Components

   Replace the faulty switch. Note that on many modern New Holland Sidewinder armrests, the switches are integrated into a Sealed Switch Module or membrane panel, requiring the replacement of the module rather than an individual toggle.

6. 6

   Reassemble and Calibrate

   Reconnect the harnesses, restore battery power, and clear the fault codes. Test the manual and auto differential lock functions in the field to confirm the repair.