Massey Ferguson 03.00.8A – TECU: High Amp Draw On Auxiliary Valve Switch 4 (TECU)

The electronic control system has detected an abnormally high electrical current draw on the circuit for the 4th auxiliary spool valve switch, typically caused by a short circuit to 0V (ground).

• 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

1. 1

   Inspect the wiring harness running from the armrest console (Auxiliary Valve Switch 4) to the TECU for pinched wires, chafing, or exposed copper shorting to ground.

2. 2

   Disconnect the plug at the fingertip switch and at the TECU to inspect pins for corrosion, moisture ingress, or melting caused by high amperage.

3. 3

   Test the wiring harness with a multimeter for a short circuit to 0V (ground).

4. 4

   Test the internal resistance of Auxiliary Valve Switch 4 to check for an internal short.

1. 1

   Power Down

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

2. 2

   Access the Switch

   Carefully remove the trim panels on the armrest console to access the underside of the auxiliary valve fingertip switches.

3. 3

   Isolate the Circuit

   Disconnect the electrical connector specifically for Auxiliary Valve Switch 4.

4. 4

   Repair Wiring (If Applicable)

   If your multimeter tests revealed a short to ground in the harness, trace the wire back to the TECU, repair the damaged section using proper soldering and heat-shrink tubing, and re-loom the harness.

5. 5

   Replace the Switch (If Applicable)

   If the wiring tests fine but the switch itself is internally shorted, unclip the faulty fingertip switch from the armrest bezel and snap the new OEM replacement switch into place.

6. 6

   Reassembly

   Reconnect the switch harness, reinstall the armrest trim panels, and reconnect the battery.

7. 7

   Clear Codes & Test

   Turn the ignition on, clear the stored 03.00.8A fault code via the tractor's diagnostic menu or a service tool, and actuate Auxiliary Valve 4 to ensure the code does not return and the valve operates smoothly.