Case IH 3650 – EDC (Electronic Diesel Control): Battery voltage: SRC high for battery voltage sensor

The control module is detecting an overvoltage condition (voltage reading is too high) from the battery voltage sensor circuit. This is typically caused by a defective alternator voltage regulator, a failed battery voltage sensor, a wiring harness short to power, or a faulty ECU.

• Farmall
• Farmall 55C
• Farmall 65C
• Farmall 75C
• Farmall 85U
• Farmall 95U
• Farmall 105U
• Farmall 115U
• JX series
• Puma
• Steiger
• SR175
• SSL
• CTL

1. 1

   Voltage Testing: Use a multimeter to check the battery's resting voltage. Then, start the engine and test the voltage under load across the battery terminals. If the voltage spikes abnormally high (e.g., well over 14.5V–15V), the alternator's internal voltage governor/regulator is defective.

2. 2

   Wiring and Ground Inspection: Inspect the battery-to-frame ground, engine block grounding, and ECU mounting grounds. Look for damaged cables, loose terminals, or sulfated battery posts.

3. 3

   Harness Inspection: Check the wiring harness between the battery voltage sensor, the alternator, and the EDC for chafing, heat degradation, or shorts to power.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to ensure safety.

2. 2

   Clean Connections

   Clean all battery terminals, cable ends, and ground connection points with a wire brush to eliminate resistance. Apply dielectric grease to prevent future corrosion.

3. 3

   Replace the Alternator

   If your diagnostic tests proved the alternator is overcharging due to a failed voltage regulator, remove the drive belt, disconnect the electrical plugs from the alternator, unbolt it from the engine bracket, and install the replacement unit.

4. 4

   Replace the Battery Voltage Sensor

   If the alternator is outputting correct voltage but the ECU still reads an SRC high fault, the battery voltage sensor itself is likely defective. Locate the sensor and replace it.

5. 5

   Test and Clear Codes

   Reconnect the battery, start the engine, and verify with a multimeter that the charging voltage is stable. Use a diagnostic tool to clear the 3650 fault code from the EDC.