Case IH 3677 – Engine Control Unit (ECU): DFC for valve position sensor voltage SRC low

The Engine Control Unit has detected that the voltage signal returning from the Exhaust Gas Recirculation (EGR) valve position sensor has dropped below the acceptable minimum threshold. This typically indicates a short to ground in the sensor circuit, a failed internal sensor, or a damaged wiring harness.

• Farmall
• skid steer
• Farmall 85A
• Farmall 95A
• Farmall 105A
• Farmall 115A
• Farmall 85C
• Farmall 95C
• Farmall 105C
• Farmall 115C
• Farmall 95U
• Farmall 105U
• Farmall 115U
• Quantum Series
• Puma
• Steiger
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• TR270B

1. 1

   Check the wiring harness and connectors between the EGR valve position sensor and the Engine Controller (EDC) for chafing, corrosion, or a short to ground

2. 2

   Verify that the sensor is receiving the proper 5V reference voltage and has a solid ground connection from the ECU

3. 3

   Remove and inspect the EGR valve for excessive carbon buildup or mechanical binding, which can cause the actuator to overwork and the sensor to read out of bounds

1. 1

   Disconnect battery

   Disconnect the machine's battery to prevent electrical shorts during service.

2. 2

   Disconnect EGR valve connector

   Locate the EGR valve assembly on the engine and disconnect the electrical connector.

3. 3

   Repair wiring harness

   If the wiring harness is damaged or shorted to ground, repair or replace the affected wiring section.

4. 4

   Clean EGR valve and tubing

   If the wiring is intact, remove the EGR valve assembly. Clean the EGR valve and the EGR tubing using a solvent to remove carbon deposits.

5. 5

   Replace EGR valve assembly

   If the position sensor (which is integrated into the EGR valve actuator) has failed electronically, install a new EGR valve assembly.

6. 6

   Reconnect components

   Reconnect the EGR valve harness and the battery.

7. 7

   Calibrate and clear codes

   Connect the Case IH Electronic Service Tool (EST). Clear the fault codes. If the EGR valve or the EDC was replaced, follow the appropriate EST procedure to restore the engine's self-learning parameters and calibrate the new valve. (Note: If the fault persists after replacing the valve and repairing wiring, the EDC itself may need to be reprogrammed or replaced).