Massey Ferguson 9034 – ECU: ECU Cut-Off Function Not Working

The ECU cut-off function failed to operate correctly during the last shutdown cycle. The Engine Control Unit requires a 'power hold' function, where a main relay maintains power for a short duration after the ignition is switched off. This allows the ECU to complete necessary internal processes, such as saving data, before fully powering down. A failure in this system prevents proper shutdown and may disrupt machine control.

• 8600 Series
• 8650
• 8660
• 8670
• 8680
• 8690
• 5400 Series
• 6400 Series
• 7400 Series
• 7600 Series

1. 1

   Check battery and power supply to ensure the battery is fully charged, terminals are clean and secure, and there is a stable voltage (a healthy battery should read approximately 12.6V with the engine off)

2. 2

   Inspect all relevant fuses for the ECU and main power circuits for blown elements

3. 3

   Visually inspect the wiring harness and connectors leading to the ECU and main relay for corrosion, damage, or loose ground connections

4. 4

   Locate the main ECU relay (power hold relay) in the engine compartment fuse and relay box

1. 1

   Test relay resistance

   Remove the main relay and use a multimeter to measure resistance across the control circuit terminals (typically 85 and 86). A normal reading is between 50 and 200 ohms. An open circuit (infinite resistance) indicates a faulty relay coil.

2. 2

   Perform relay function test

   Apply a 12V power source to the control circuit terminals (85 and 86). Listen for an audible 'click'. While energized, check for near-zero resistance (continuity) between the power-switching terminals (30 and 87).

3. 3

   Test the relay socket

   If the relay tests good, turn the key on and verify 12V power at the coil supply terminal (85 or 86) and a good ground on the opposite terminal. Verify a constant 12V supply at the power input terminal (30).

4. 4

   Replace the main relay

   If the relay fails the resistance or function tests, or does not click when energized, replace it with a new unit matching the correct amperage rating.