Massey Ferguson 10.02.26 – AC Module (AIRCON): Missing Engine Coolant Temperature Signal On The CAN BUS

The Air Conditioning (AIRCON) control module relies on engine coolant temperature data to regulate cab climate and prevent AC system operation if the engine is overheating. The AIRCON module is reporting that the expected CAN message containing the coolant temperature data from the Engine ECU is either invalid, missing, or timed out.

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4700 Series
• 4707
• 4708
• 4709
• 4710
• 5600 Series
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5700 SL Series
• 7600 Series
• 7700 Series
• 8600 Series

1. 1

   Check for accompanying engine codes in the Engine ECU for primary coolant temperature sensor faults

2. 2

   View the live data stream in the Engine ECU to verify if it reads the coolant temperature accurately

3. 3

   Perform a CAN bus network test to check for other missing CAN bus communication codes (e.g., engine speed or vehicle speed)

4. 4

   Visually inspect the wiring harnesses and connectors between the Engine ECU and the AC Module for corrosion, moisture ingress, or chafed wires (specifically the CAN High and CAN Low twisted pair)

1. 1

   Disconnect Battery

   Always disconnect the negative battery terminal before probing or repairing CAN bus wiring or replacing sensors.

2. 2

   Address Sensor Issues

   If Step 1 of your diagnostics revealed a faulty sensor, locate the Engine Coolant Temperature Sensor on the engine block/thermostat housing. Unplug the connector, remove the old sensor, install the replacement, and torque to OEM specifications. Reconnect the harness.

3. 3

   Repair CAN Wiring

   If the sensor is working but the signal isn't reaching the AC module, locate the break or short in the CAN bus wiring. Repair any damaged sections of the CAN High/CAN Low wires using proper soldering and heat-shrink techniques to maintain network resistance.

4. 4

   Clean Connectors

   Disconnect the main harness connectors at both the Engine ECU and the AIRCON module. Spray with electrical contact cleaner, ensure no pins are pushed back or bent, and apply dielectric grease before reconnecting.

5. 5

   Clear Codes and Test

   Reconnect the battery. Use a diagnostic tool to clear the 10.X.26 / 10.00.26 fault code from the AIRCON module. Start the tractor, allow it to reach operating temperature, and verify that the AC system functions correctly without the code returning.