New Holland ENG 3650 – Engine Control Unit (ECU): Battery Voltage: SRC high for battery voltage sensor

This fault code indicates that the Engine Control Unit (ECU) is detecting an abnormally high battery supply voltage. The ECU continuously monitors the battery voltage, and this code triggers when the voltage signal exceeds the maximum allowable threshold (SRC high), which typically points to an overcharging condition or a short circuit.

• L213
• L216
• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238
• W50C
• W60C
• W70C
• W80C
• CR9090
• CX8080 Elevation
• CX8090 Elevation
• T8 Series
• Magnum 235-340 Series 4

1. 1

   Use an Electronic Service Tool to check if the fault is currently active. Clear the code, start the machine, and operate it to see if the code returns.

2. 2

   Test the alternator and battery with a multimeter to verify if the alternator is actually overcharging the system (voltage significantly higher than 14V).

3. 3

   Inspect the wiring harness between the battery, alternator, and ECU. Look specifically for a short to the positive battery or an open circuit.

1. 1

   Document and Clear

   Connect your Electronic Service Tool. Write down the fault code, number of occurrences, and engine hours at the last occurrence. Clear the fault code.

2. 2

   Test Operation

   Start the engine and operate the machine. If the fault code does not record again, the machine is OK to return to service (likely a transient voltage spike).

3. 3

   Inspect Harness

   If code 3650 returns, visually inspect the wiring harness and ECU connectors for damage, corrosion, or exposed wires that could cause a short to power.

4. 4

   Test Alternator Output

   Measure the voltage at the battery while the engine is running. If the voltage is too high (e.g., above 15-16 volts), the alternator's internal voltage regulator has failed.

5. 5

   Replace Components

   If the alternator is overcharging, replace the alternator assembly. If the charging voltage is normal but the ECU still reads high voltage, repair the shorted wiring harness. If wiring and charging voltage are both perfect, the ECU itself (or its internal voltage sensor) has failed and requires replacement/reprogramming.