John Deere 29.04 – ECU: Secondary Throttle Signal Out of Range Low

This fault indicates that the voltage signal from the secondary throttle sensor (typically the hand throttle) has fallen below the acceptable low-voltage threshold expected by the ECU. This condition is usually caused by a faulty throttle sensor, degraded wiring, poor electrical connections, or a short to ground/open circuit. When triggered, the system may enter a safety mode that reduces engine power to prevent unpredictable throttle response.

• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5M Series
• 6010-6510 Series
• 6320
• 6420
• 7610
• 7710
• 7810
• J-Series
• 1654
• 1854
• 2054
• 2104
• 6165J
• 6185J
• 6205J
• 6210J
• 316GR
• 318G
• 331G
• 333G
• 304J
• 4.5L PowerTech Electronic Fuel System engine
• 6.8L PowerTech Electronic Fuel System engine
• 8.1L PowerTech Electronic Fuel System engine

1. 1

   Inspect the physical hand throttle linkage for binding, damage, or improper adjustment.

2. 2

   Inspect the throttle sensor connector and all circuit wiring for wear, corrosion, or loose connections to rule out wiring issues.

3. 3

   Measure the resistance of the throttle potentiometer and the throttle circuit wiring to check for an open circuit or a short to ground.

4. 4

   Verify the vehicle's battery and alternator voltage, as a broader system voltage drop can cause the ECU to read the sensor signal as low.

5. 5

   Connect to John Deere Service Advisor or Diagnostic Scan Tool (DST) and run the Harness Diagnostic Mode Test to monitor throttle voltage in real-time.

1. 1

   Turn ignition off

   Ensure the machine is turned off and the key is removed before disconnecting any electrical components.

2. 2

   Repair wiring

   If the diagnostic checks revealed degraded wiring or corroded connector terminals, repair or replace the damaged harness sections.

3. 3

   Replace throttle sensor

   If the wiring is intact but the potentiometer failed the resistance test (or outputs voltage below the threshold), remove the faulty hand throttle potentiometer and install a new OEM replacement.

4. 4

   Reset system

   Reconnect the battery/ignition, connect the Service Advisor or DST, and clear the stored 000029.04 fault code.

5. 5

   Test operation

   Thoroughly test the hand throttle across all ranges (from idle to full throttle) to ensure the engine responds appropriately and the code does not return.