Massey Ferguson 00.00.4C – Dash: Issue With Signal From Outside Air Temperature Sensor (Dash)

The controller is receiving an implausible signal from the ambient air temperature sensor. This is typically caused by an open circuit, a short circuit to ground, or a short circuit to positive in the sensor's wiring, or a complete failure of the sensor's internal thermistor.

• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• Tier 4 (2015-2021)

1. 1

   Locate the outside ambient air temperature sensor on the exterior of the cab near the fresh air intake, under the roof overhang, or near the exterior mirror brackets.

2. 2

   Inspect the 2-pin electrical connector and the wiring harness leading to the sensor for broken wires, rubbed insulation causing a short to the chassis, or green corrosion inside the connector pins.

3. 3

   Disconnect the sensor and use a multimeter to check the harness side for continuity to the Dash module, ensuring there is no short to ground or short to positive voltage.

4. 4

   Measure the resistance across the two pins of the sensor itself. A healthy sensor typically reads around 5,000 Ohms (5kΩ) at standard room temperature. If it reads completely open (infinite resistance) or zero resistance, the sensor is dead.

1. 1

   Turn off the tractor ignition and disconnect the battery

   to prevent any electrical spikes.

2. 2

   Disconnect the 2-pin wiring harness from the faulty outside air temperature sensor.

3. 3

   Unclip or unbolt the sensor from its mounting bracket.

4. 4

   Clean the harness connector with electrical contact cleaner

   if any dirt or mild oxidation is present.

5. 5

   Snap the new OEM replacement sensor into the mounting bracket.

6. 6

   Reconnect the 2-pin wiring harness

   ensuring the weather-pack seal clicks firmly into place.

7. 7

   Reconnect the battery and turn on the tractor ignition.

8. 8

   Use a diagnostic scan tool (or the tractor's onboard dash diagnostic menu) to clear the 00.00.4C fault code.

9. 9

   Verify the repair by checking the dashboard display

   to ensure it is now reading a plausible outside ambient temperature.