The Nexus is a generator-set controller. It is used on generator sets from Generac and Nexus, including the Not explicitly stated, QT 130, QT017 and QT022.
Used across brands: Generac, Nexus
Also fitted to: Generac 005873-1, Generac 005875-1, Generac 005885-1, Generac 005886-1, Generac 005887-1, Generac 006053-1, Generac 10 KW, Generac 6 kW, Generac 8-20 kW.
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| 0 | Utility failure | Crank and start engine, transfer load to Generator if Utility returns above 75% nominal for 15 seconds | |
| 000001 | DANGER | ||
| 1100 | Condition - Engine Cranks but will not Start (5 crank attempts) | Unit turns over but will not start. Controller is receiving signal on Wire 18. | Problem 17 |
| 1200 | Prolonged (60 Hz on a 50 Hz unit, 72Hz on 60Hz unit) Overspeed | Overspeed for 3 seconds. Possible cause: Stepper motor/mixer body assembly issue. | Test 12 |
| 1205 | Instantaneous (62 Hz on a 50 Hz unit, 75Hz on 60Hz unit) Overspeed | Overspeed for 0.1 second (100 milliseconds). Possible cause: Stepper motor/mixer body assembly issue. | Test 12 |
| 1300 | Occurred while running | Check oil level and pressure. Test 61 | |
| 1400 | Condition - Air Flow Impeded / Flow Issue | Check the inlet/outlet for debris. Check temperature sensor and wiring. Test 62 | |
| 1501 | RPM Sensor ALARM | ||
| 1501 | Twin Cylinder+Running | Twin Cylinder Running faults to RPM Sensor Loss. Possible Causes: air pocket in fuel line, dirty fuel, missing ignition pulse (loss of one of the primary coils). | Test 50 and Test 64 |
| 1505 | Twin Cylinder+Cranking | Twin Cylinder Cranking faults to RPM sensor loss Possible Cause: starter motor issue, missing ignition pulse (loss of one of the primary coils). If engine cranks, Test 64. If engine does not crank, Problem 15. | |
| 1511 | Single Cylinder+Running | Single Cylinder Running RPM sensor loss Possible Causes: air pocket in fuel line, dirty fuel. Loss of ignition pulse. | Test 50 and Test 64 |
| 1515 | Single Cylinder+Cranking | Single Cylinder Cranking faults to RPM sensor loss Possible Causes: starter motor issue, missing ignition pulse (loss of one of the primary coils). If engine cranks, Test 64. If engine does not crank, Problem 15. | |
| 1900 | Prolonged Over-Voltage Undervoltage | ||
| 1901 | Instantaneous Undervoltage | ||
| 1902 | Undervoltage | ||
| 2099 | Wiring Error ALARM | ||
| 2100 | Stepper Overcurrent ALARM | ||
| 2102 | Overloaded ALARM | ||
| 2399 | Overload Remove Load ALARM | ||
| Battery is Dead | Problem 22 – Battery is Dead | Test 45 – Check Battery and Cables | |
| Evolution E-Code 2400 | Engine Will Not Crank When Utility Power Source Fails | Test 44 – Check 7.5 Amp Fuse Evolution Alarm Code 2400 | |
| Evolution Fault codes 1800 - 1803 and 2101 | Generator Shuts Down for Over Voltage | ||
| Evolution Fault codes 1800 - 1803 and 2101 | Generator Shuts Down for Overload / Over Voltage | ||
| Evolution Fault codes 1900 - 1906 | Generator Shuts Down for Under Voltage | ||
| FuelSys006 | Fuel System Fault | ||
| Generator Will Not Exercise | Problem 20 – Generator Will Not Exercise | Test 45 – Check Battery and Cables | |
| No Low Speed Exercise | Problem 21 – No Low Speed Exercise | ||
| Problem 18 | Shutdown Alarm/Fault Occurred |
| Symptom | Cause | Remedy |
|---|---|---|
| AUTO/OFF/MANUAL Switch at OFF, engine continues to run. | Defective AUTO/OFF/MANUAL switch; Open/disconnected wire #15A between AUTO/OFF/MANUAL switch and Control Module circuit board; Defective Control Module circuit board | 1. Replace switch; 2. Reconnect/close wire; 3. Replace board |
| Engine cranks but won't start. | Out of fuel; Fuel solenoid (FS) is defective; Open Wire #14A from Engine Control circuit board; Spark plugs defective; Door on tank not closed | 1. Replenish fuel; 2. Replace solenoid; 3. Reconnect wire; 4. Clean, regap or replace plugs; 5. Close door on tank |
| Engine speed and frequency drop excessively under load | Engine may be underpowered; result of dirty air cleaner, loss of engine compression, faulty fuel settings, or incorrect ignition timing | Refer to Section 4.5 Diagnostic Tests for repair procedures |
| Engine starts hard, runs rough. | Flame arrestor (air cleaner) plugged or damaged; Plugged fuel line; Defective spark plugs; Fuel pressure incorrect | 1. Clean or replace as needed; 2. Unclog fuel line; 3. Clean, regap or replace plugs; 4. Confirm fuel pressure to regulator is as recommended in SPECIFICATIONS |
| Engine starts then shuts down. | Engine oil level is low; Engine is overheated; Defective Low Oil Pressure Switch; Defective Coolant Temperature Switch; Defective Control Module circuit board; Coolant Level is Low; Defective Low Coolant Level Switch | 1. Check oil and add oil as needed; 2. Check cooling system for leaks; 3. Replace switch; 4. Replace switch; 5. Replace board; 6. Repair leak - Add coolant; 7. Replace Switch |
| Engine won’t crank. | 15 amp fuse blown; Loose or corroded or defective battery cables; Defective starter contactor; Defective starter motor; Dead or Defective Battery; 5 amp fuse blown | 1. Replace fuse; 2. Tighten, clean or replace battery cables as necessary; 3. Replace contactor; 4. Replace starter motor; 5. Remove, change or replace battery |
| Generator Produces High Voltage | TEST 1 - CHECK AC OUTPUT VOLTAGE, HIGH -> TEST 11 - CHECK AC OUTPUT FREQUENCY, HIGH -> TEST 12 - CHECK STEPPER MOTOR CONTROL, REFER TO PROBLEM 1, TEST 3 - CALIBRATE VOLTAGE, VOLTAGE OUTPUT AT BREAKER IS BELOW 220 OR ABOVE 270 VOLTS -> VOLTAGE OUTPUT AT BREAKER IS BETWEEN 220-270 VAC -> FREQUENCY O.K., BUT VOLTAGE INCORRECT -> FREQUENCY AND VOLTAGE O.K. -> STOP TESTS | |
| Generator Produces High Voltage at No-Load | TEST 14 - CHECK AC OUTPUT FREQUENCY TEST 16 - CHECK STEPPER MOTOR CONTROL TEST 2 - CHECK AC OUTPUT VOLTAGE | |
| Generator Produces Low Voltage at No-Load | TEST 14 - CHECK AC OUTPUT FREQUENCY TEST 16 - CHECK STEPPER MOTOR CONTROL TEST 2 - CHECK AC OUTPUT VOLTAGE | |
| Generator Produces Zero Voltage or Residual Voltage | TEST 1 - CHECK MAIN CIRCUIT BREAKER TEST 4 - PERFORM FIXED EXCITATION / ROTOR AMP DRAW PERFORM STATOR INSULATION RESISTANCE TEST - SECTION 1.4 PERFORM ROTOR INSULATION RESISTANCE TEST - SECTION 1.4 TEST 7 - TEST STATOR TEST 5 - WIRE CONTINUITY TEST 6 - FIELD BOOST TEST 11 - CHECK ROTOR RESISTANCE CHECK VOM FUSES TEST 12 - CHECK BRUSHES & SLIP RINGS TEST 13 - TEST ROTOR ASSEMBLY REPAIR OR REPLACE FUSES | |
| Generator Shuts Down for Under Voltage | Perform FBCT, Preliminary Output Voltage Test (if Evolution non-Synergy with Firmware v1.12 or higher), TEST 4 - Fixed Excitation / Rotor Amp Draw, RE-TEST, REPLACE CONTROLLER if necessary, CHECK DMM FUSES, TEST 5 - SENSING CIRCUIT WIRES 11 AND 44, BAD -> TEST 6 - EXCITATION WINDING CIRCUIT 2 AND 6, BAD -> TEST 8 - RESISTANCE CHECK OF ROTOR CIRCUIT, GOOD -> TEST 7 - TEST STATOR, BAD -> PERFORM STATOR INSULATION RESISTANCE, REPLACE STATOR ONLY if necessary, TEST 10 - TEST ROTOR ASSEMBLY, BAD -> REPLACE ROTOR AND STATOR, BAD -> REPAIR OR REPLACE, BAD -> ROTOR CIRCUIT FAILURE, TEST 9 - CHECK BRUSHES & SLIP RINGS, GOOD -> BAD -> TEST 10 - TEST ROTOR ASSEMBLY, GOOD -> TEST 7 - TEST STATOR, BAD -> REPLACE ROTOR ONLY, BAD -> REPLACE ROTOR AND STATOR, PERFORM ROTOR INSULATION RESISTANCE TEST | |
| High Temperature ALARM | Check the inlet/outlet for debris. Check temperature sensor and wiring. | |
| Low Oil Pressure ALARM | Occurred while running The default Extended alarm for low oil pressure. Check oil level and pressure. | |
| No AC output from generator. | Check main line circuit breaker; Check circuit breaker & fuses; Transfer switch set to NORMAL position; Generator internal failure; Thermal circuit breaker open | 1. Reset to ON or CLOSED; 2. Reset and replace, if necessary; 3. Set to GENERATOR position; 4. *; 5. Auto-reset - Wait 5 min. and attempt restart |
| Overspeed ALARM | Prolonged (60 Hz on a 50 Hz unit, 72Hz on 60Hz unit) Over specified Hz for 3 seconds. Possible cause: Stepper motor/mixer body assembly issue. | |
| Unstable Voltage or Incorrect Output Which is Not Triggering a Shutdown | TEST 1 - CHECK AC OUTPUT VOLTAGE, ERRATIC -> PROCEED TO PROBLEM 3 | |
| Voltage and Frequency Drop Excessively When Loads Are Applied | TEST 14 - CHECK VOLTAGE AND FREQUENCY UNDER LOAD, BOTH LOW -> TEST 15 - CHECK FOR OVERLOAD CONDITION, NOT OVERLOADED -> GOOD -> IF RECONFIGURED TO LP GAS, VERIFY THAT PROPER PROCEDURE WAS FOLLOWED (REFER TO INSTALLATION MANUAL), GOOD -> OVERLOADED -> DISCONTINUE TESTING, REDUCE LOADS TO UNIT’S RATED CAPACITY, TEST 12 - CHECK STEPPER MOTOR CONTROL, GOOD -> BAD -> REPAIR OR REPLACE, LOOK FOR A SHORTED CONDITION IN A CONNECTED LOAD OR IN ONE OF THE LOAD CIRCUITS, GOOD -> TEST 7 - CHECK STATOR AC POWER WINDINGS, ENGINE CONDITION GOOD -> REPAIR OR REPLACE, BAD -> TEST 16 - CHECK ENGINE CONDITION, GOOD -> GO TO “PROBLEM 18 - ENGINE STARTS HARD AND RUNS ROUGH/LACKS POWER” SECTION 4.3 |
Fault codes and symptom→remedy steps extracted from this controller’s service/owner documentation; verify against the official manual before servicing. Aggregated from the service documentation of generator sets built on this controller.