Case IH 3676 – Engine ECU (EDC): DFC for valve position sensor voltage SRC high

Signal Range Check (SRC) failure where the voltage signal from the Exhaust Gas Recirculation (EGR) Valve Position Sensor is higher than the maximum plausible limit. This is typically caused by a short circuit to a power source, an open ground circuit on the sensor harness, or an internal failure of the EGR position sensor itself.

• Farmall
• skid steer
• Farmall 35C
• Farmall 105C
• Farmall 105U
• Farmall 115U
• Magnum
• Steiger
• SR175
• 580N
• 586H

1. 1

   Visual Inspection: Inspect the wiring harness and connectors between the EGR valve position sensor and the Engine ECU (EDC) for chafing, melted insulation, or corrosion.

2. 2

   Circuit Testing: Check the sensor signal wire for a short to voltage (SRC high) and verify the sensor ground circuit is intact (an open ground will cause the signal voltage to default high).

3. 3

   Mechanical Inspection: Remove the EGR valve and inspect for heavy soot or carbon buildup.

4. 4

   Scan Tool Verification: Use the CNH Electronic Service Tool (EST) to monitor the live voltage data of the EGR valve position sensor while manipulating the wiring harness to check for intermittent shorts.

1. 1

   Disconnect Power

   Turn off the battery quick disconnector or disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Wiring Repair

   If a short to power or open ground was found during diagnostics, repair the damaged section of the wiring harness or replace the connector pigtail.

3. 3

   Component Replacement

   If the wiring tests good, the EGR valve position sensor has failed internally. Depending on the specific engine model, replace the sensor on its own or replace the entire EGR Valve Assembly.

4. 4

   Reassembly

   Install the new sensor or EGR valve, ensuring the mating surfaces are clean and new gaskets are used. Reconnect the electrical harness.

5. 5

   ECU Reset and Relearn

   Reconnect the battery. Connect the CNH EST and clear the inactive fault codes.

6. 6

   Calibration

   If the EGR valve was replaced, you must perform an 'ECU Data Reset' via the EST. Run the engine until the coolant temperature reaches at least 65°C (149°F) to allow the ECU to relearn the EGR valve end-stops and verify the fault does not return.