Massey Ferguson 03.02.9B – TECU: High Voltage On Auxiliary Valve Switch 8 (TECU)

The controller is receiving a voltage signal from the switch controlling the 8th auxiliary (spool) valve that is higher than the expected normal operating range. This condition is typically caused by a short to power in the switch's signal wire, an open ground circuit, or an internal failure (short) within the switch itself.

• 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
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 8600 Series
• 8S Series

1. 1

   Visually inspect the wiring harness routing from the armrest console or fender switch to the TECU for chafed insulation, pinched wires, or damaged connectors.

2. 2

   Using a multimeter, back-probe the signal wire for Auxiliary Valve Switch 8 at the switch connector. Check if voltage reads at full system voltage (12V) or reference voltage (5V) without actuation.

3. 3

   Disconnect the switch to isolate the component. If the high voltage on the signal wire drops to 0V, the switch is internally shorted. If high voltage remains, the harness is shorted to power.

4. 4

   Verify the ground circuit for the switch. A broken or corroded ground wire will prevent the voltage from dropping, causing a constant high state.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Access the Switch

   Depending on the tractor's configuration, carefully remove the plastic trim or console cover using non-marring pry tools to access Auxiliary Valve Switch 8 on the Multipad joystick or armrest console.

3. 3

   Disconnect

   Unplug the electrical connector from the faulty switch.

4. 4

   Remove

   Depress the retaining tabs or remove the mounting screws holding the switch in the console bezel, and pull the switch out.

5. 5

   Install

   Snap the new OEM switch into the console and reconnect the wiring harness.

6. 6

   Reassemble

   Reinstall the armrest/joystick covers and trim pieces.

7. 7

   Test & Clear

   Reconnect the battery. Turn the ignition on, use a diagnostic tool to clear the 03.02.9B code, and actuate the switch to ensure the auxiliary valve responds correctly without throwing a new code.