Massey Ferguson 03.00.8B – TECU: High Voltage On Auxiliary Valve Switch 4 (TECU)

The system has detected a Short circuit to 12 V on the circuit for Auxiliary Valve Switch 4 (commonly referred to as FingerTIP switch 4). The signal voltage returning to the controller is higher than the maximum allowed operating range, indicating that power is bypassing the normal resistance of the switch or sensor.

• 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 physical condition of Auxiliary Valve Switch 4 (FingerTIP 4) on the armrest console for liquid intrusion (e.g., spilled drinks or rain).

2. 2

   Disconnect the electrical connector at Auxiliary Valve Switch 4, turn the key ON, and re-check active fault codes. If the code changes to Low Voltage or Open Circuit, the short is internal to the switch. If 03.00.8B remains, the short is in the harness.

3. 3

   Use a multimeter to check the signal wire at the switch connector for continuity to a 12V power source.

1. 1

   Power Down

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

2. 2

   Access the Armrest Internals

   Carefully remove the upper plastic housing of the armrest console to expose the FingerTIP switches and the Autotronic 5 module wiring.

3. 3

   Address the Short

   If the switch is faulty: Unclip Auxiliary Valve Switch 4 from the armrest bezel. Plug the new replacement switch into the harness and snap it back into the console. If the harness is faulty: Trace the signal wire from the switch back to the TECU. Locate the area where the wire insulation has rubbed through and is contacting a 12V power wire. Repair the damaged wire using solder and heat-shrink tubing, then re-wrap the harness with friction tape.

4. 4

   Reassembly & Calibration

   Reassemble the armrest console. Reconnect the battery. Turn the key ON and clear the inactive fault codes. Note: You may need to perform a spool valve calibration procedure via the Datatronic screen after replacing a fingertip switch.