John Deere 1490 – ACU: Feeder House Speed Signal Voltage Feedback Out of Range

The signal voltage feedback for the feeder house speed is greater than 4.93 VDC (on a 5V circuit), non-existent, or intermittent. This out-of-range condition means the feeder house backshaft speed is unknown to the Armrest Control Unit (ACU). Operating with this fault poses a risk of severe damage to the feeder house if the reverser is engaged while the backshaft is still rotating.

• 9410
• 9510
• 9610
• 9540
• 9560
• 9580
• 9640
• 9660
• 9680
• 9660 STS
• 9760 STS
• 9860 STS
• 9770

1. 1

   Visually inspect for any physical obstructions or plugging of the feeder house, cylinder, or augers that could impede rotation.

2. 2

   Inspect the feeder house backshaft (typically on the right-hand side) and ensure the sensor actuator wheel is securely fastened to the shaft.

3. 3

   Verify the magnetic pickup speed sensor is mounted securely on its bracket and that the bracket itself is not loose.

4. 4

   Inspect the wiring harness and circular plastic (sure seal) connectors between the sensor and the Armrest Control Unit for breaks, chafing, corrosion, or loose connections.

5. 5

   Perform a basic electrical test on the 2-wire magnetic pickup sensor: disconnect it, connect a voltmeter set to AC voltage, spin the shaft, and verify it generates a fluctuating AC voltage.

1. 1

   Prepare machine for service

   Shut off the engine, set the parking brake, and remove the key before beginning any repair.

2. 2

   Clear obstructions

   If any plugging of the feeder house or related components was found during inspection, clear the obstruction to allow free rotation.

3. 3

   Secure sensor components

   If the sensor wheel or mounting bracket is loose, tighten the set screws or bolts to secure them. Use a collar if needed to keep the sensor wheel in the correct position.

4. 4

   Repair or replace wiring

   Repair any damaged wiring or connectors found in the harness. If the damage is extensive, replace the right side feederhouse backshaft speed sensor wiring harness.

5. 5

   Replace speed sensor

   If the sensor failed the AC voltage output test (no voltage generated when the shaft spins), replace the magnetic pickup sensor.

6. 6

   Clear codes and calibrate

   Clear the fault codes from the control unit. Consult the operator's manual to perform any required feeder house function calibrations (such as feeder house raise speed) and test operate the machine to ensure the code does not return.