John Deere HMM201000 – HMM: Grain Too Dry To Measure

This fault code is an informational alert indicating that the moisture content of the grain passing over the sensor is below the minimum threshold the system can accurately measure. It is classified as a Service Alert priority, meaning it typically represents a status message about exceptionally dry operating conditions rather than a critical hardware malfunction.

• 9570 STS
• 9670 STS
• 9770 STS
• 9870 STS

1. 1

   Verify if the crop being harvested is actually at a very low moisture level.

2. 2

   Check for other active HMM diagnostic trouble codes that could indicate a hardware malfunction (e.g., motor, plunger, or relay failures).

3. 3

   Inspect the moisture sensor for gummed-up residue that could affect accuracy.

4. 4

   Verify the moisture sensor's temperature calibration against ambient temperature.

5. 5

   Check if a general moisture calibration is needed due to inaccurate readings or recent component replacement.

1. 1

   Acknowledge the code

   Recognize that the system is indicating the grain moisture is below its measurement range.

2. 2

   Verify Accuracy

   If you suspect the grain is not as dry as the system suggests, proceed with diagnostics.

3. 3

   Clean the sensor

   Access the moisture sensor and clean the sensing surfaces using glass cleaner. Do not use harsh solvents like brake cleaner or abrasives like emery cloth.

4. 4

   Run calibrations

   Perform the moisture sensor temperature calibration (ideally at the beginning of the day before combine heat affects it) and the general moisture calibration through the combine's display.

5. 5

   Address mechanical faults

   If other HMM codes are present (such as HMM 523105.14 for a stalled motor), remove the plunger to clean out trapped grain, adjust the inlet plate to be snug against the plunger, and slow down the sample rate via system settings.