Massey Ferguson 3.X.8A – TECU: High Amp Draw On Auxiliary Valve Switch 4 (TECU)

A "Short circuit 0 V" (short to ground) on the circuit for the 4th auxiliary valve switch.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Visual Inspection: Inspect the wiring harness routing from the TECU (Armrest Autotronic 5) to the fingertip switch for Auxiliary Valve 4. Look for pinched wires, chafing against the armrest frame, or melted insulation.

2. 2

   Circuit Testing: Disconnect the switch and use a digital multimeter to check the signal wire for continuity to ground.

3. 3

   Component Testing: Test the Auxiliary Valve Switch 4 itself to see if the internal contacts have failed and shorted to ground.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent further electrical damage.

2. 2

   Access the Switch

   Carefully disassemble the armrest control console to access the underside of the fingertip switches (spool valve controls).

3. 3

   Disconnect and Isolate

   Unplug the electrical connector specifically for Auxiliary Valve Switch 4.

4. 4

   Test the Harness

   Probe the harness-side connector with a multimeter. If the short to ground is present on the harness side while disconnected from the switch, trace the wiring back to the Autotronic 5 module and repair the chafed/shorted wire.

5. 5

   Test/Replace the Switch

   If the harness tests fine, the short is internal to the switch. Remove the faulty fingertip switch from the armrest bezel and install a new one.

6. 6

   Reassembly and Clearing

   Reconnect the switch, reassemble the armrest console, reconnect the battery, and clear the stored DTCs. Test the operation of the 4th auxiliary valve to ensure the code does not return.