Fendt 1E.1.34 – Engine Control Unit (ECU) / EDC 7: Coolant outside of setpoint level / Coolant level too low

The system has detected that the coolant level in the expansion tank has dropped below the minimum required threshold, or there is a signal fault in the sensor circuit.

• 309 Vario COM III
• 310 Vario COM III
• 311 Vario COM III
• 312 Vario COM III
• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 409 Vario COM III
• 410 Vario COM III
• 411 Vario COM III
• 412 Vario COM III
• 711 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 815 Vario COM III
• 817 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• 916 Vario COM III & S4
• 920 Vario COM III & S4
• 922 Vario COM III & S4
• 924 Vario COM III & S4
• 926 Vario COM III & S4
• 927 Vario COM III & S4
• 930 Vario COM III & S4
• 933 Vario COM III & S4
• 936 Vario COM III & S4
• 939 Vario COM III & S4

1. 1

   Visual Inspection: Physically check the coolant level in the expansion tank. If it is low, check the engine and cooling system for leaks.

2. 2

   Sensor Testing: Test the S034 switch located at the top of the engine on the coolant reservoir (Separation point X244). When the coolant level is OK, resistance should be approx. 160 ohms and signal voltage approx. 0.45 VDC. When low, signal voltage should read approx. 10.3 VDC.

3. 3

   Wiring Check: Inspect the wiring harness and connector at the S034 switch for a broken wire or short circuit. Refer to the 'EDC control' or 'Dashpanel' circuit diagrams.

4. 4

   Software Diagnostics: Connect the SERDIA (Service Diagnostics) program to read the fault log (FC:0025) and view live sensor values.

1. 1

   Locate expansion tank

   Open the tractor bonnet and locate the coolant expansion tank at the top of the engine.

2. 2

   Top up coolant and pressure-test

   If the coolant is physically low, top it up to the specified setpoint level and pressure-test the cooling system to ensure there are no leaks.

3. 3

   Disconnect switch

   If the coolant level is correct but the fault remains active, disconnect the S034 coolant level switch.

4. 4

   Test switch

   Test the switch using a multimeter based on the voltage/resistance values mentioned in the diagnostic steps.

5. 5

   Replace switch

   If the switch is faulty (e.g., stuck open or internally shorted), unscrew the old sensor from the expansion tank and install a new OEM replacement.

6. 6

   Reconnect wiring

   Reconnect the wiring harness.

7. 7

   Clear fault code

   Connect the SERDIA diagnostic tool and clear the stored fault code (FC:0025) from the EDC memory.