Massey Ferguson 03.02.87 – TECU: High Voltage On Auxiliary Valve Switch 3 (TECU)

The controller is receiving a signal voltage from the 3rd auxiliary hydraulic spool valve switch (typically a fingertip proportional switch located on the armrest) that exceeds the maximum expected operating range. This condition is usually caused by a short circuit to a 12V power source, a broken ground wire, an internal failure of the switch's potentiometer, or lost calibration parameters.

• 7724S
• 5712SL
• 7722S
• 7722
• 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

1. 1

   Inspect the wiring harness running from the armrest console to the TECU for pinched wires, chafing, or exposed copper that could be shorting the signal wire to a 12V power source.

2. 2

   Disconnect the Auxiliary Valve Switch 3 at the armrest and inspect the pins for corrosion, moisture, or damage. Do the same at the TECU harness junction.

3. 3

   With the key ON, use a multimeter to check the reference voltage and ground at the switch connector. Ensure the ground circuit is intact; an open ground will cause the signal voltage to float high.

4. 4

   Test the resistance of the switch potentiometer while moving the fingertip lever. If the resistance is out of limits or shows an open/short circuit internally, the switch is faulty.

1. 1

   Disconnect Power

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

2. 2

   Access the Switch

   Remove the retaining screws on the armrest console to access the underside of the fingertip spool switches.

3. 3

   Remove the Faulty Switch

   Unplug the electrical connector for Auxiliary Valve Switch 3. Unclip or unscrew the switch assembly from the armrest housing.

4. 4

   Install the New Part

   Seat the new electric spool switch into the armrest and secure it. Reconnect the wiring harness.

5. 5

   Reassemble

   Put the armrest console back together and reconnect the tractor's battery.

6. 6

   Clear Codes and Calibrate

   Turn the ignition ON. Use a compatible diagnostic tool (such as Jaltest or the Massey Ferguson dealer tool) to clear the inactive 03.02.87 fault code.

7. 7

   Calibration

   You must calibrate the new valve switch through the tractor's display terminal or diagnostic tool. The TECU needs to learn the new minimum, maximum, and neutral voltage values of the replacement potentiometer.