Massey Ferguson D138 – Dash (Instrument Panel / Cluster): Issue With Signal Voltage From Gear Shift Lever, T Handle Low Signal Voltage

The controller is receiving a voltage signal from the armrest gear shift lever (T-handle) potentiometer that is below the minimum expected operating threshold, typically pointing to an open circuit, a short to ground, a loss of reference voltage, or an internal failure.

• MF 8650
• MF 8680
• Interim Tier 4 (2012-2015)
• 7615
• 5613
• MF 8480
• MF 8450
• 7616
• 7618
• 5608
• 7619
• 7626
• MF 8660
• 7624
• MF 8690
• 7614
• MF 8470
• 5610
• 7620
• MF 8600
• MF 8460
• MF 8670
• 5612
• 7622
• 5611
• 5609
• MF 5700 Series
• 5710
• 5711
• 5712
• 5713
• MF 7600 Series
• MF 8400 Series
• MF 8600 Series
• 8670
• 8690

1. 1

   Inspect the main wiring connection under the armrest to ensure it is securely fastened and not contaminated or corroded.

2. 2

   Verify the 12V supply line and the 5V reference voltage at the potentiometer terminals.

3. 3

   Test the potentiometer signal line between the armrest lever and the controller for an open circuit or a short to ground.

1. 1

   Replace potentiometer

   If the wiring is intact but the signal voltage remains out of specification, the potentiometer/T-handle assembly must be replaced.

2. 2

   Navigate to calibration menu

   Turn on the tractor's display and navigate to the calibration menu.

3. 3

   Select calibration icon

   Select the armrest lever calibration icon and press 'OK'.

4. 4

   Verify neutral position

   The screen will display the current position of the lever (which should read 'Neutral' on the first line).

5. 5

   Push lever forward

   Push the T-handle lever fully forward to the '+' position. The value on the first line will change to register the new maximum parameter.

6. 6

   Save calibration

   Follow the on-screen prompts to save the calibration and clear the D138 fault code.