John Deere 29.03 – Engine Control Unit (ECU): Secondary Analog Throttle Signal Out of Range High

Triggers when the secondary analog throttle voltage (typically the hand throttle, decelerator pedal, or secondary throttle) exceeds the high voltage threshold specified for the sensor. This abnormally high voltage usually indicates electrical interference, a malfunctioning throttle potentiometer/sensor, or a wiring fault (such as a short to power or an open circuit) that artificially elevates the signal.

• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 6010
• 6020
• 6920S
• 331G
• 333G
• 210L EP
• 540G-III
• 548G-III
• 460E

1. 1

   Connect a diagnostic scan tool to verify the active code and monitor the live voltage reading of the secondary/hand throttle sensor.

2. 2

   Inspect the wiring harness and connectors between the hand throttle potentiometer and the Engine ECU for corrosion, moisture, or physical damage to the pins.

3. 3

   Use a multimeter to check the sensor wiring for an open circuit or a short to power, which is the most common cause of an 'Out of Range High' voltage reading.

4. 4

   Test the hand throttle potentiometer's resistance/voltage output to determine if the sensor itself has failed internally and is sending a voltage higher than the specified range.

1. 1

   Power Down

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Sensor

   Locate the hand throttle potentiometer/sensor, which is typically mounted directly to the hand throttle lever assembly in the cab.

3. 3

   Disconnect and Inspect

   Unplug the sensor's electrical connector. Clean the contacts with electrical contact cleaner if dirt or light corrosion is present.

4. 4

   Repair Wiring (If Applicable)

   If the diagnostic circuit test revealed a short to power or broken wire in the harness between the sensor and the ECU, repair or replace the affected wiring harness section.

5. 5

   Replace the Sensor

   If the wiring is intact and the sensor failed the voltage/resistance test, remove the mounting hardware securing the hand throttle potentiometer and install a new OEM replacement sensor.

6. 6

   Reassemble and Calibrate

   Reconnect the sensor harness and the battery. Turn the ignition on (engine off).

7. 7

   Clear Codes and Test

   Use the diagnostic scan tool to clear the 000029.03 fault code. Operate the hand throttle through its full range of motion while monitoring the live voltage data to ensure it stays within the normal operating range and the code does not return.