Massey Ferguson 03.X.86 – TECU (Tractor Electronic Control Unit): High Amp Draw On Auxiliary Valve Switch 3 (TECU)

A short circuit to 0 V (Short to Ground) on the circuit for the third auxiliary valve switch (FingerTIP switch), causing an excessive amperage draw that the controller detects, disabling the circuit to prevent electrical damage.

• 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
• 5608-5613
• 5710SL-5713SL
• 6600 Series
• 6700 Series
• 7600 Series
• 7700 Series
• 7614-7626
• 7714-7726
• 8400 Series
• 8700 Series
• 8450
• 8460

1. 1

   Visually inspect the armrest console and the specific FingerTIP switch for Auxiliary Valve 3 for physical damage, liquid intrusion, or stuck buttons

2. 2

   Disconnect the switch and use a digital multimeter to check the wiring harness between the switch and the TECU (Armrest Autotronic 5) for continuity to ground (0 ohms indicates a rubbed or pinched wire)

3. 3

   Test the switch itself for an internal short (fused or shorted contacts)

4. 4

   Inspect the X104 connector at the TECU for corrosion, moisture, or bent pins bridging the circuit to ground

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery cable to prevent further electrical damage or accidental shorting during repair.

2. 2

   Access the Armrest

   Carefully remove the cladding/cover panels on the right-hand armrest console to expose the FingerTIP switch bank and wiring.

3. 3

   Disconnect the Switch

   Locate Auxiliary Valve Switch 3 and unplug its electrical connector.

4. 4

   Repair the Short

   If the diagnostic tests proved the wiring harness is shorted to ground, locate the pinched/rubbed section, repair the wire, and protect it with heat-shrink tubing or loom. If the switch tested faulty (internal short), remove the mounting screws/clips and extract the old switch.

5. 5

   Install New Part

   Snap or screw the new switch into the armrest support bracket and reconnect the wiring harness.

6. 6

   Reassemble and Clear Codes

   Reinstall the armrest covers, reconnect the battery, and turn the key on. Use a diagnostic tool to clear the 03.X.86 / AR 31 fault code and test the hydraulic valve operation.