John Deere 111.07 – Engine Control Unit (ECU): Engine Coolant Level Switch Mismatch or Coolant Level Circuit Fault

The coolant level monitor is without function, or there is a mechanical/electrical fault in the coolant level circuit.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8310RT
• 8335RT
• 8360RT
• 7760 Cotton Picker / Stripper
• Articulated Dump Trucks

1. 1

   Verify Coolant Level: Physically check the coolant level in the surge tank/radiator to see if it is actually low.

2. 2

   Inspect for Leaks: Check the entire cooling system for signs of leakage.

3. 3

   Intermittent Check: Observe if the Diagnostic Trouble Code (DTC) periodically 'goes away' on its own, which can point to a loose connection rather than a hard failure.

4. 4

   Circuit Testing: Inspect the wiring harness connected to the Engine Coolant Level Switch. Check for a 'Short-To-Ground' or open circuit on the sensor wiring (e.g., checking the yellow signal wire on the harness).

1. 1

   Clean and Inspect

   Clean the radiator and check the physical coolant level.

2. 2

   Top Off Fluids

   If the coolant is low, add John Deere COOL-GARD (or an equivalent low-silicate ethylene/propylene glycol base coolant) and inspect for leaks.

3. 3

   Cycle Ignition

   In many cases, turning the ignition key off and on or following the instructions on the CommandCenter™ page will resolve the code if it was triggered by a temporary slosh or low fluid event.

4. 4

   Inspect the Sensor

   Locate the Engine Coolant Level Switch (typically located at the bottom of the surge tank). Check the connector for corrosion, moisture, or backed-out pins.

5. 5

   Replace the Switch

   If the wiring is intact, the fluid is full, and the code persists, the coolant level switch has failed mechanically or electrically and must be replaced.

6. 6

   Final Verification

   Clear the codes. If the code returns immediately after replacing the sensor and verifying the wiring, the issue may require a John Deere dealer to flash or update the ECU software, as some models had software updates specifically to prevent false setting of Coolant Level DTCs.