John Deere 3841.02 – XMC / XSC: Wheel Angle Sensor (WAS), Voltages in Channel 1 and Channel 2 are Not in the Correct Ratio

The wheel angle sensor contains two separate internal sensors (channels). Under normal operation, the signal voltage of Sensor 2 should be exactly half (1/2) of the signal voltage of Sensor 1 (a 1:2 ratio). This code is triggered when the system detects a difference of 0.4 volts or more from this expected ratio, even if the overall voltage values still fall within the acceptable operating range. When this fault occurs, the control software will exhibit limited or no AutoTrac/steering functionality to prevent erratic steering behavior.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6145J
• 6165J
• 6180J
• 6205J
• 7200R through 7310R
• 7R 210 to 7R 350
• 8225R to 8400R
• 8R 230 to 8R 410
• 9370R to 9620RX
• S550
• S650
• S660
• S670
• S680
• S690
• 4940
• R4030
• R4038
• R4044
• R4045
• R4060
• 8000 Series Forage Harvesters
• 9000 Series Forage Harvesters

1. 1

   Monitor Sensor Voltages: Use Service ADVISOR to monitor the voltages of both WAS channels in real-time to verify if the 1:2 voltage ratio is deviating or intermittently dropping.

2. 2

   Inspect Wiring and Connections: Check the wiring harness connected to the wheel angle sensor for physical damage, chafing, disconnection, or corrosion. Ensure all connections are secure.

3. 3

   Verify Sensor Mounting: Ensure the sensor and its linkage are securely mounted and properly aligned. Loose or worn linkages can cause erratic mechanical inputs.

4. 4

   Check for Electrical Interference: Inspect nearby components for potential sources of electrical interference that could skew the sensor's analog voltage signals.

5. 5

   Check Software Versions: Check for any available updates for the XMC/XSC control software to address potential signal processing bugs.

1. 1

   Repair Wiring

   If the diagnostic checks reveal damaged wiring or corroded connector pins, repair or replace the affected wiring harness section.

2. 2

   Replace the Sensor

   If the wiring is intact but the sensor fails to maintain the 1:2 voltage ratio on the diagnostic tool, the internal potentiometers of the sensor have failed. Replace the Wheel Angle Sensor with a new OEM part.

3. 3

   Install and Align

   Install the new sensor, ensuring the connection shaft/adapter and linkage are properly seated and not binding.

4. 4

   Update Software

   Flash the XMC/XSC control unit with the latest software payload if an update is available.

5. 5

   Calibrate and Clear Codes

   After replacing the sensor, perform the Wheel Angle Sensor calibration procedure via the machine's display/Service ADVISOR. Once calibrated, clear the 003841.02 diagnostic trouble code and test drive to verify the AutoTrac system functions correctly.