Case IH 3700 – Engine Control Unit (ECU): Humidity Sensor : Plausibility check for the humidity sensor signal

The intake air humidity sensor is sending a signal value that the system determines is not plausible based on the current operating conditions or baseline parameters. This occurs when the analog sensor signal falls outside the maximum and minimum allowed captured values, or if there is a short circuit.

• Magnum 180
• Magnum 225
• Magnum 235
• Magnum 250
• Magnum 340 CVT
• Puma series
• Farmall series
• 240 Series Axial-Flow combines
• AFX series

1. 1

   Check the wiring harness leads connected to the humidity sensor for a Short circuit to Battery (SCB) or Short circuit to Ground (SCG)

2. 2

   Ensure the electrical connector at the humidity sensor is securely fastened and free of corrosion or debris

3. 3

   Using a diagnostic scan tool, verify the live analog sensor signal to ensure it does not fall outside the acceptable minimum and maximum range

1. 1

   Locate the humidity sensor, which is mounted on the engine air intake tube.

2. 2

   Cut any wire ties securing the wiring harness to the sensor.

3. 3

   Carefully disconnect the electrical connector from the humidity sensor (and the adjacent air restriction sensor, if applicable).

4. 4

   If access is restricted, disengage the hose clamps on each end of the air intake tube and temporarily remove the tube.

5. 5

   Remove the faulty humidity sensor from its mounting point.

6. 6

   Install the new humidity sensor.

7. 7

   Reinstall the air intake tube and tighten the hose clamps (if removed).

8. 8

   Reconnect the electrical harness to the humidity sensor and secure the wiring with new wire ties.

9. 9

   Clear the fault codes using a diagnostic tool and run the engine to ensure the code does not return.