John Deere 2931.03 – CCU: Foot Brake Oil Level Switch High Volts

The CCU is reading a voltage signal from the brake oil level switch circuit that is higher than the normal operating range. This typically points to an open circuit, a disconnected sensor, a broken wire, or a short to a high-voltage source in the brake circuit wiring.

• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 5050E
• 5058E
• 5067E
• 5075E
• 5M Series
• 6M Series
• WB-series

1. 1

   Verify brake fluid level in the reservoir is between the ADD and FULL marks.

2. 2

   Inspect the brake oil level switch connection on the reservoir for corrosion, moisture, or pushed-back terminals.

3. 3

   Test the wiring harness between the brake oil level switch and the CCU for severed wires (open circuit) or chafing (short to power).

4. 4

   Test the switch continuity using a multimeter to ensure contacts are open when the reservoir is full and closed when the float drops.

1. 1

   Prepare the Machine

   Park the tractor on a level surface, lower any attachments to the ground, engage the parking brake, and turn the key switch to the OFF position.

2. 2

   Access the Reservoir

   Locate the brake fluid reservoir and clean the area around the cap and sensor to prevent contamination of the brake circuit.

3. 3

   Remove the Faulty Sensor

   Disconnect the electrical harness from the brake oil level switch. If the switch is threaded into the reservoir, use a syringe to extract enough brake fluid to drop the level below the sensor port to prevent spills. Carefully unscrew or unclip the faulty switch.

4. 4

   Install the New Sensor

   Install the replacement brake oil level switch.

5. 5

   Refill and Bleed

   Top up the brake fluid reservoir with the specified John Deere brake fluid/hydraulic oil (e.g., Hy-Gard) to the correct level. If air entered the brake lines during the repair, bleed the brake circuit.

6. 6

   Clear Codes

   Reconnect the electrical harness. Turn the ignition on and use the Monitor Display Unit or a diagnostic service tool to clear the CCU diagnostic trouble codes.

7. 7

   Test

   Start the engine and test the foot brakes to ensure proper operation and verify that the code does not return.