1904
What This Code Means
Undervoltage (both zero crosses missing for 1.5 seconds); Undervoltage (little / no voltage, <120V); Undervoltage (no field current but have DPE); Generator Shuts Down for Under Voltage; Undervoltage; Prolonged Undervoltage; Generator voltage below 80% of nominal for 10+ seconds.; Both Zero Crosses missing Undervoltage; Controller measuring no voltage resulting in undervoltage; Generator voltage less than 120V when undervoltage set; No field current during undervoltage alarm; Generator running underspeed for > 30 seconds when under - voltage alarm set; Single Zero Cross missing Undervoltage; After resuming from a load shed event, still undervoltage because of overload condition.; Generator Xfer Enabled Output has been mis - wired.; Incorrect DC AC wiring hook up.
Possible Causes
- •Faulty excitation winding
- •Faulty zero cross circuit
- •Circuit in general
- •Loose wiring
- •Field boost hardware failure
- •Controller measuring no voltage
- •Wire loose
- •Brush failure
- •Faulty Main Circuit Breaker
- •Faulty Fixed Excitation Circuit
- •Faulty Rotor Insulation Resistance
- •Faulty Regulator Output
- •Faulty AC Sensing Circuit
- •Faulty Brushed Rotor Assembly
- •Faulty Stator
- •Faulty DPE Breaker
- •Faulty DPE Circuit
- •Faulty Flash Wiring
- •Faulty DB1 Diode
- •Faulty DB2 Diode
Suggested Actions
- 1Test Main Circuit Breaker
- 2Test Fixed Excitation
- 3Perform Rotor Insulation Resistance Test
- 4Test Regulator Output
- 5Test AC Sensing Circuit
- 6Test Brushed Rotor Assembly
- 7Test Stator
- 8Test DPE Breaker
- 9Test DPE Circuit
- 10Test Flash Wiring
- 11Test DB1 Diode
- 12Test DB2 Diode
- 13Test Wire 14 Field Flash Circuit
- 14Test Field Flash Circuit
- 15Replace Controller
- 16Replace Stator Only
- 17Replace Rotor Only
- 18Replace Rotor and Stator
- 19Repair or Replace Wire 14
- 20Repair or Replace Rotor
ASK RUDY ABOUT THIS FAULT
Get a diagnosis walkthrough for 1904 on your specific Generac unit — cited to the OEM manual, not a forum guess.
TRY IT FREE