John Deere 524203.04 – ATC (Automatic Temperature Control) Module: Low Voltage On Ambient Air Temp Cab Roof Above Right Side Front Corner

The control unit measures 0 volts at the signal input for the front ambient air temperature sensor (B125, lead 2001), typically indicating a short to ground in the circuit. As a result, the HVAC system receives no data from the ambient air temperature sensor, which can cause the climate control system to operate on default settings or erroneous data, reducing cabin comfort.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6105M
• 6115M
• 6125M
• 6130M
• 6140M
• 6150M
• 6170M
• 7R Series Tractors
• 6230
• 6330
• 6430
• 9430
• 9530
• 9630
• E360
• E360LC
• E240LC
• 4720
• 4730
• 4830
• 4930
• 4940

1. 1

   Inspect the front ambient air temperature sensor (B125) wiring and connections at lead 2001 for physical damage, corrosion, or pinched wires.

2. 2

   Disconnect the sensor and use a multimeter to check for continuity to ground on the signal wire (lead 2001) to identify a short.

3. 3

   Turn the key ON and measure the reference voltage at the sensor connector to confirm if the 0-volt reading is due to a wiring short or a failed ATC module output.

1. 1

   Access the Sensor

   Safely access the right side front corner of the cab roof to reach the B125 Ambient Air Temperature Sensor.

2. 2

   Repair Wiring

   If the multimeter test revealed a short to ground in the harness (lead 2001), trace the harness back toward the ATC module, repair the damaged wire(s), and secure them with heat shrink and loom to prevent future chafing.

3. 3

   Replace the Sensor

   If the wiring tests perfectly fine and the short is internal to the sensor itself, remove the faulty B125 sensor and install the replacement part.

4. 4

   Test Sensor Functionality

   Reconnect the sensor and turn the machine ON. Verify that the ATC module is now reading a realistic ambient air temperature rather than defaulting.

5. 5

   Clear Codes and Functional Test

   Clear the 524203.04 fault code from the ATC system using a diagnostic tool or the cab monitor. Run the HVAC system through a full operational test to ensure the climate control functions correctly.