John Deere 1872.18 – SCO: Front Hitch Position Sensor Circuit Voltage Low

The controller is detecting that the voltage signal returning from the front hitch position sensor is below the acceptable threshold. This typically indicates an open circuit, a short to ground in the wiring harness, or an internal failure of the sensor itself.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 7200R
• 7210R
• 7215R
• 7230R
• 7250R
• 7260R
• 7270R
• 7280R
• 7290R
• 7310R

1. 1

   Locate the Front Hitch Position Sensor, designated as component B535 in the electrical schematics.

2. 2

   Inspect the wiring harness and the connector at the B535 sensor for physical damage, corrosion, pushed-back pins, or moisture intrusion.

3. 3

   Perform a Front Hitch Position Sensor Circuit Test. Check for a short to ground or an open circuit on the signal wire returning to the SCO module. Verify that the sensor is receiving the correct reference voltage (usually 5V) and has a solid ground.

4. 4

   Check if the sensor has lost its mechanical linkage or calibration parameters (sometimes accompanied by code 9006).

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery ground if you will be repairing wiring.

2. 2

   Access the Sensor

   Locate the B535 rotary position sensor on the front hitch assembly.

3. 3

   Wiring Repair

   If the diagnostic circuit test revealed a short to ground or broken wire, repair the harness using approved John Deere electrical splices and heat shrink.

4. 4

   Sensor Replacement

   If the wiring is intact and the reference voltage/ground are correct, the Hall Effect sensor has failed internally. Disconnect the electrical connector, unbolt the sensor from the front hitch position sensor plate, install the new sensor (AE74688), and ensure the rotary linkage is properly engaged with the hitch arm.

5. 5

   Calibration

   After replacing the sensor, you must perform a hitch calibration procedure via the tractor's CommandCenter display or using the John Deere Service Advisor tool so the SCO module can learn the new minimum and maximum voltage values for the hitch's physical travel limits.