New Holland TMF 32 – Instrumentation Controller: Ground Speed Signal is failed in the Instrumentation Controller

The tractor's computer is not receiving a valid or stable speed signal from the ground speed sensor (or radar sensor), which can result in erratic speedometer readings and the transmission limiting gear selection (e.g., refusing to shift into higher gears, such as above 13th gear).

• TS-A Series
• TS100A
• TS115A
• TS135A
• TM Series
• TM120
• TM155
• TM190
• T-Series
• T4
• T5
• T6
• T7
• T8
• T9
• TG Series
• TG305
• Magnum
• Maxxum
• Puma
• Steiger

1. 1

   Verify symptoms: Check if the tractor's speedometer is reading erratically (e.g., jumping from 12 mph to 16 mph) or if the transmission is locked out of higher gears.

2. 2

   Inspect wiring and connectors: Check the wiring harness and the connector at the ground speed sensor for corrosion, moisture, or broken wires.

3. 3

   Perform sensor swap test: On certain models where the ground speed sensor is identical to the engine speed sensor, temporarily interchange them to see if the fault follows the sensor.

4. 4

   Physically inspect the sensor: Remove the ground speed sensor and inspect the tip. A cracked or damaged tip indicates physical contact with internal transmission/axle components.

1. 1

   Prep the Machine

   Park the tractor on a level surface, turn off the engine, and disconnect the battery to prevent electrical shorts during the swap.

2. 2

   Locate the Sensor

   The ground speed sensor is typically located on the right side of the rear axle housing (just in front of the axle) or on the side of the transmission housing. Note: On some models like the TS115A, you may need to remove a hydraulic filter to gain adequate access to the sensor.

3. 3

   Remove the Sensor

   Disconnect the electrical pigtail. Unbolt and carefully pull the old sensor out. It may be seated very tightly due to O-ring swelling or debris.

4. 4

   Install the New Sensor

   Lubricate the O-ring on the new sensor slightly, press it into the housing, and secure it with the mounting bolt.

5. 5

   Reconnect

   Plug the electrical connector back in and reconnect the tractor's battery.

6. 6

   Calibration (If Applicable)

   If you are replacing a Radar True Ground Speed Sensor, a field calibration is highly recommended to establish the correct Pulses Per Mile/Kilometer (PPM/PPKM) in the display monitor.

7. 7

   Test Drive

   Operate the tractor to verify that the speedometer reads smoothly and the transmission successfully shifts through all upper gears.