New Holland TMF 86 – Instrumentation Controller: Wheel Slip Signal is failed in the Instrumentation Controller

The system is unable to calculate the tractor's wheel slip percentage. This occurs when the controller loses the signal from the transmission/wheel speed sensor or the radar speed sensor, or if the signals are implausible.

• T5 Series
• T6 Series
• T7 Series
• T7.175
• T7.210
• T8 Series
• T8040
• T9 Series
• TG Series
• TG215
• TM Series
• Magnum
• Steiger
• Maxxum

1. 1

   Visually inspect the face of the radar sensor for heavy mud, dirt, or crop debris, which can block the radar signal and cause a false failure.

2. 2

   Inspect the wiring harness running from the radar speed sensor and the transmission wheel speed sensor to the Instrumentation Controller for chafed wires, open circuits, short circuits, or corroded connector pins.

3. 3

   Using a digital multimeter, verify that the sensor is receiving the correct reference voltage from the controller and check the signal wire for continuity.

4. 4

   Look for accompanying codes (like TMF 87 for Ground Speed Signal failure) which can help isolate whether the issue is the radar sensor or the transmission speed sensor.

1. 1

   Clean the Sensor

   Park the tractor on a level surface, turn off the engine, and thoroughly clean the face of the radar speed sensor. Restart the tractor and check if the code clears.

2. 2

   Repair Wiring

   If the wiring harness is damaged or connectors are corroded, clean the pins with electrical contact cleaner or splice in a new repair pigtail.

3. 3

   Replace the Sensor

   If the wiring is intact but the sensor has failed internally, disconnect the sensor's electrical connector, unbolt the sensor from its mounting bracket, install the new radar speed sensor or wheel speed sensor, tighten the mounting hardware, and reconnect the wiring harness.

4. 4

   Clear Codes and Calibrate

   Clear the TMF 86 fault code from the Instrumentation Controller. Perform a radar/slip calibration procedure as outlined in the operator's manual (typically involving driving the tractor a measured distance on a hard, flat surface to sync the radar and wheel speeds).