Massey Ferguson 04.01.94 – Transmission Controller (TRANS): CAN BUS Communication Issue Between Transmission And Arm Rest Module (TRANS)

This indicates a loss of data or a communication breakdown on the CAN (Controller Area Network) bus circuit specifically between the tractor's armrest control module (where the operator inputs commands like gear shifts and shuttle controls) and the transmission control unit.

• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• Tier 4 (2015-2021)
• 7700 Series
• 7700S Series

1. 1

   Check CAN Bus Terminators: Bench test the CAN bus terminators. Supply 12 volts to terminal 1 and ground to terminal 3. Measure the voltage between terminal 4 (CAN Low) and terminal 3. The voltage should read between 2.4 to 2.6 volts.

2. 2

   Inspect Wiring and Connectors: Check the wiring harness running between the armrest module and the transmission controller. Look for chafed wires, shorts to ground, or broken connections.

3. 3

   Check Battery and Alternator Voltage: Low battery voltage or alternator issues can cause CAN bus modules to drop offline. Ensure the battery is fully charged and the alternator is outputting correct voltage.

4. 4

   Check for Correlated Codes: Look for other CAN bus errors (such as D 149 'CAN network deactivated' or D 150 'CAN messages lost') which might indicate a broader network failure rather than an isolated module issue.

1. 1

   Disconnect Power

   Disconnect the tractor's battery before servicing any CAN bus wiring or electronic modules to prevent short circuits.

2. 2

   Clean and Reseat Connectors

   Disconnect the main harness at the armrest module and the transmission controller. Inspect the pins for corrosion, moisture, or bent terminals. Clean with electrical contact cleaner, apply dielectric grease, and firmly reseat the connectors.

3. 3

   Repair Wiring

   If the multimeter continuity tests reveal a break or short in the CAN High or CAN Low lines between the armrest and the transmission, splice and repair the damaged section of the wiring harness.

4. 4

   Replace Faulty Module

   If the wiring harness and terminators test perfectly, the fault lies internally within either the Armrest Control Module or the Transmission Controller. Replace the suspect module.

5. 5

   Recalibrate / Reprogram

   If a module is replaced, use a compatible diagnostic tool (such as an AGCO diagnostic tool or Jaltest) to copy configurations, flash the correct software version, and calibrate the transmission and armrest joystick.