John Deere 523967.02 – TIA, UIC, or ACU: Speed Band Switch and Voltage Mismatch

Indicates a conflict or mismatch between the position of the Speed Band switch (Speed Band 1 or 2) and the corresponding analog voltage readings from the potentiometer on the speed control lever (S108 or B67). The control unit will typically limit the functionality of the speed control lever to prevent operational errors.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 8310RT
• 8335RT
• 8360RT

1. 1

   Inspect the physical condition of the speed control lever (B67 / S108) to ensure it is properly positioned and not mechanically binding or damaged.

2. 2

   Inspect the Speed Band switch for physical defects or operational issues that might impair its ability to correctly modify or represent voltage changes.

3. 3

   Using a multimeter, measure the actual voltage output when the Speed Band switch is engaged to ensure readings correspond accurately with the switch position and the potentiometer's expected values.

4. 4

   Inspect all wiring and connectors related to the speed control lever and speed band switches for signs of wear, damage, corrosion, or loose pins causing intermittent voltage discrepancies.

1. 1

   Recalibrate the Switch/Lever

   If the switch, lever, and wiring are physically intact, attempt to recalibrate or adjust the switch settings via the tractor's diagnostic monitor to align with the expected voltage outputs.

2. 2

   Repair Wiring

   If any damaged wiring or corroded connectors were found during the diagnostic checks, repair or replace the affected harness sections.

3. 3

   Replace the Speed Band Switch

   If recalibration does not correct the voltage mismatch, or if there is evidence of mechanical failure inside the switch, replace the Speed Band switch.

4. 4

   Replace the Speed Control Lever

   If the potentiometer (B67/S108) on the speed control lever is found to be faulty and is sending incorrect voltage ratios that cannot be calibrated, replace the entire speed control lever/sensor unit.

5. 5

   Clear Codes and Test

   After replacing components or repairing wiring, clear the fault codes and test the tractor's speed bands in operation to ensure the voltage mismatch is resolved.