Massey Ferguson 03.01.9B – TECU: High Voltage On Auxiliary Valve Switch 8 (TECU)

The control module is receiving a voltage signal from the switch that controls Auxiliary Spool Valve 8 that exceeds the normal operating parameters. This condition typically indicates a short circuit to power (12V) in the switch or its wiring harness, or an open circuit on the ground/reference side.

• 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
• 5700 series
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 6700 series
• 7600 series
• 7700 series
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7625
• 7626
• 7725
• 8600 series
• 8S series

1. 1

   Identify the location of Auxiliary Valve Switch 8 (typically on the armrest console, Fingertip switch/Multipad joystick, or rear fender).

2. 2

   Inspect the wiring harness and connectors between the switch and the TECU for chafed wires, pinched harnesses in pivot points, or corrosion.

3. 3

   Perform a voltage test by disconnecting the switch and checking the signal wire voltage with the key on. If high voltage remains, the short is in the harness.

4. 4

   Check for related fault codes, such as 03.01.9A (High Amp Draw on Switch 8) or 03.01.9C (Calibration Issue for Valve Switch 8).

1. 1

   Power Down

   Turn off the tractor and disconnect the battery isolator to prevent electrical spikes during repair.

2. 2

   Access the Switch

   Remove the trim panels on the armrest console or the fender housing to access the back of Auxiliary Valve Switch 8.

3. 3

   Disconnect and Replace/Repair

   If the diagnostic tests pointed to a harness short, repair the damaged section of the wiring and apply heat-shrink tubing. If the harness tested fine, the internal potentiometer/contacts of the switch have failed. Unclip the faulty switch from the console and plug in the replacement switch.

4. 4

   Reassemble and Power Up

   Reinstall the console trim and reconnect the battery.

5. 5

   Clear Codes and Calibrate

   Clear the inactive 03.01.9B fault code from the TECU. You will likely need to perform a switch calibration procedure via the tractor's Datatronic terminal, as replacing the switch often triggers code 03.01.9C until the new switch's parameters are learned.