Massey Ferguson 10.01.25 – AC Module (AIRCON): No Vehicle Speed Information Received On The CAN BUS To AC Module (AIRCON)

A network communication error where the AC Control Module stops receiving the 'Vehicle Speed' signal broadcasted by the main Engine ECU or Transmission controller over the CAN bus.

• 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
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614 through 7626
• 7714 through 7726S

1. 1

   Verify the tractor's main dash display is showing vehicle speed while moving to rule out a faulty main Vehicle Speed Sensor (VSS)

2. 2

   Check for accompanying codes in the Engine ECU or Transmission TCU related to the vehicle speed sensor

3. 3

   Inspect the CAN bus wiring harness leading to the AC module for chafing, rodent damage, or pinched wires

4. 4

   With the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the AC module connector (should read approximately 60 ohms)

1. 1

   Disconnect the Battery

   Always disconnect the negative battery terminal before servicing CAN bus components to prevent voltage spikes.

2. 2

   Address the Speed Sensor (If Applicable)

   If diagnostic step 1 revealed a dead speedometer, locate the Vehicle Speed Sensor on the transmission housing. Clean the sensor tip (magnetic sensors gather metal shavings) and check its pigtail connector. Replace the sensor if it fails a multimeter resistance test.

3. 3

   Clean AC Module Connectors

   If the speed sensor is fine, access the AC Control Module (typically located in the cab roof or behind the right-hand console depending on the series). Unplug the module and inspect the pins for green corrosion, moisture, or pushed-back terminals. Clean with electrical contact cleaner and apply dielectric grease.

4. 4

   Repair CAN Wiring

   If you find an open circuit on the CAN High or CAN Low wires leading to the AC module, splice and repair the broken wire using OEM-approved heat-shrink connectors to restore network communication.

5. 5

   Replace/Reprogram the AC Module

   If the wiring is perfectly intact, the main ECU is broadcasting speed, and the connector pins are clean, the AC module's internal CAN transceiver has likely failed. The module must be replaced and potentially flashed/calibrated by a dealer to recognize the tractor's specific CAN architecture.