John Deere 974.03 – ACU, EPC, UIC, or ECU / ECM: Hand Throttle Sensor Circuit Voltage Problem

The control unit measures a voltage in excess of 4.7 volts at the signal input of the hand throttle potentiometer (sensor B96, lead 6018). This indicates a short to a positive power lead, an open circuit in the sensor wiring, or a problem with the ground connection, which leads to degraded throttle control and engine performance.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6010-6910
• 6M series
• 6R series
• 7720
• 7810
• 7820
• 7920
• 7R series
• 8130
• 8230
• 8330
• 8430
• 8530
• 8R series
• 8310RT
• 8335RT
• 8360RT
• 9230
• 9330
• 9430
• 9530
• 9630
• 9R series
• 9470RT
• 9520RT
• 9570RT
• John Deere 3029
• PowerTech engines

1. 1

   Inspect the wiring harness and connectors leading to the hand throttle potentiometer (B96) for signs of physical damage, loose pins, or corrosion.

2. 2

   Verify that the ground connection in the potentiometer's circuit is secure and free of corrosion, as a lost ground will cause the signal voltage to spike high.

3. 3

   Use a multimeter to inspect the signal circuit (lead 6018) for any signs of shorting to a positive voltage source or an open circuit.

4. 4

   Test the hand throttle potentiometer's sweep functionality using a diagnostic tool (like John Deere Service ADVISOR) or a multimeter. The voltage should smoothly transition without jumping to 5V or dropping out.

1. 1

   Power Down

   Turn off the engine and place the machine in park. Disconnect the battery if repairing wiring.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short to power, an open wire, or a bad ground, repair or replace the affected section of the wiring harness.

3. 3

   Replace Sensor

   If the wiring is intact but the sensor fails the sweep test or internally shorts to 5V, remove the mounting screws/clips holding the hand throttle potentiometer in the armrest/dash console and disconnect the electrical plug. Install the new potentiometer.

4. 4

   Reassemble and Reconnect

   Plug the sensor back in and secure it to the console.

5. 5

   Reset and Test

   Turn the key on, clear the active codes via the CommandCenter display or Service ADVISOR, and test the hand throttle to ensure smooth engine RPM response and verify the code does not return.