John Deere 03 – CAB: Unloading Auger Light Activated When Commanded Off

The control unit detects voltage in the unloading auger light circuit when it has commanded the light to be off. Normally, this light should only illuminate when the main field lights are on and the unloading auger is swung out past a predetermined angle (e.g., more than 10 or 50 degrees). This fault indicates a discrepancy between the commanded state and the actual state, typically caused by a short circuit to power, a faulty auger position sensor sending a false extended signal, or a wiring harness issue.

• 9660 STS
• 9670 STS
• 9760 STS
• 9770 STS
• 9860 STS
• 9870 STS
• 9880 STS
• S660
• S670
• S670H
• S680
• S680H
• S685
• S685H
• S690
• S690H
• 9400
• 9500
• 9600

1. 1

   Verify the condition: Check if the unloading auger light is on with the field lights off (indicating a direct short) or only when field lights are on but the auger is stowed (indicating a control logic or sensor issue)

2. 2

   Check the auger position sensor or limit switch at the auger's pivot point for failure or false signals

3. 3

   Visually inspect the wiring harness leading to the unloading auger light and position sensor for damage, chafing, or corrosion, paying close attention to the auger pivot point

4. 4

   Check the light bulb and housing for an internal short circuit

1. 1

   Access Diagnostic Trouble Codes

   Use the combine's display to confirm the exact fault code and verify whether the CAB or LC1 control unit logged the fault.

2. 2

   Test the Auger Position Sensor

   For rotary sensors (like part number AH215263), view the live voltage reading through the combine's diagnostic addresses; voltage should change as the auger swings. If stuck at a high voltage when stowed, the sensor is faulty. For limit switches, unplug the harness and test for continuity changes (open to closed or vice-versa) when the auger moves.

3. 3

   Inspect and Test the Wiring

   Disconnect the harness at the control unit and the unloading auger light. Use a multimeter to check for a short to power on the position sensor signal wire and the light power wire (should be 0V when commanded off). Also check the light circuit ground wire for continuity to ground. A bad ground can sometimes cause unpredictable electrical behavior.

4. 4

   Isolate and Repair the Fault

   If a short circuit is found in the harness, repair or replace the damaged section. The 'Short Unloading Auger Light Wiring Harness' (part number AH211711) may be a relevant replacement part. If the position sensor tests faulty, replace it. If both test good, suspect a faulty relay (if applicable) or control unit.