ATC 001549.03 – Heater Valve (Adjusting Motor) Voltage Too High. John Deere System Advisory.

ATC 001549.03 (ATC 1549.03)

Code: 001549.03

Shortcode: 1549.03


The error code, ATC 001549.03, is triggered when the control unit measures excessive voltage at the motor connecting leads (2016 and/or 2027) for the heater valve (B131). This high voltage typically indicates a short in the circuit, which can affect the operation of the heater valve’s adjusting motor. Such conditions can lead to malfunctioning or failure of the heater valve, affecting the heating performance within the vehicle’s cabin.


The excessive voltage could potentially damage the heater valve motor or related electrical components, leading to improper heating control. This may result in uncomfortable cabin temperatures and increased wear on the HVAC system


  • Inspect Wiring and Connections: Examine the wiring and connections at leads 2016 and 2027 for any signs of damage, corrosion, or improper connections that might lead to a short circuit.
  • Measure Voltage Levels: Use a multimeter to verify the voltage at the specified leads. Elevated readings can confirm the presence of a short.
  • Identify and Repair Short Circuits: Locate and repair any shorts within the circuit. Replace damaged wires or connectors as necessary.
  • Test Heater Valve Operation: After making electrical repairs, test the heater valve and its motor to ensure they are operating correctly and regulating cabin temperature effectively.
  • Reset System and Verify Operation: Clear any stored fault codes and perform a comprehensive system test to ensure all components function correctly and that the issue has been resolved.


Regular maintenance of the HVAC system’s electrical components is crucial to prevent voltage irregularities that can lead to system failure. Ensuring that all connections are secure and components are functioning properly helps maintain the effectiveness and reliability of the heating system, thereby enhancing occupant comfort and vehicle safety.

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