The Automatic Voltage Regulator (AVR) is a generator-set controller. It is used on generator sets from Cummins/Onan, Denyo, Northern Lights and Stamford/AvK, including the MX321, DCA-10LSX, DCA-15LSX and DCA-18ESX.
Used across brands: Cummins/Onan, Denyo, Northern Lights, Stamford/AvK
Also fitted to: Stamford/AvK PI734D, Stamford/AvK PM734B, Stamford/AvK SX460, Stamford/AvK SX460 AUTOMA.
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| The FAULT 1 or FAULT 2 lamp comes on and the engine shuts down | Engine runs until fault shutdown due to fault indication switches | Service as required; if shutdown was due to low frequency, check for fuel supply or governor adjustment issues; if shutdown was due to over/under voltage, check voltage regulator | |
| The HI ENG TEMP lamp comes on and the engine shuts down | Engine runs until fault shutdown due to high engine temperature | Check engine coolant level, repair any coolant leaks and refill as necessary; reset ECM if set still shuts down; start engine and observe coolant temperature as system heats up; replace high engine temperature cutout switch if shutdown occurs before coolant reaches 230° F (110° C); clean and service cooling system as required to restore full cooling capacity | |
| The LO OIL PRES lamp comes on and the engine shuts down | Engine runs until fault shutdown due to low oil pressure | Check engine oil level, repair any oil leaks and fill to proper level; reset ECM if set still shuts down; service lubricating oil system according to engine service manual if oil pressure is less than 14 psi (97 kPa); replace low oil pressure cutout switch if oil pressure is greater than 14 psi (97 kPa) | |
| The OVERSPEED lamp comes on and the engine shuts down | Engine runs until fault shutdown due to overspeed | Overspeed module (PMG equipped sets) or overspeed switch cannot be adjusted; governor adjustment issue; linkage binding; speed pick-up unit output voltage less than 2.5 VDC; actuator unit does not drive the linkage through its full travel when power is connected or return it when power is disconnected; governor controller issues | Reset ECM, adjust governor, repair and adjust linkage as necessary, re-install magnetic speed pick-up unit to ensure correct clearance with flywheel gear teeth, replace speed-pickup unit if output voltage at cranking speed is less than 2.5 VDC, replace actuator or governor controller |
| Symptom | Cause | Remedy |
|---|---|---|
| A Fault Shutdown is being indicated by one of the red lights on the control panel. | Service the set as necessary. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Run. | |
| A LO Shutdown is being indicated on the day tank pump control panel. | Determine the cause and service as necessary (See Section 7). To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Run or Remote. Note that the engine control will shut down unless the day tank control has been reset first. | |
| A) the light emitting diode (LED) indicator, just above the UFRO Control potentiometer, being permanently lit when the generator is on load, and b) poor voltage regulation on load, i.e. operation on the sloping part of the characteristic | Clockwise adjustment lowers the frequency (speed) setting of the “knee point’ and extinguishes the LED. For Optimum setting the LED should illuminate as the frequency falls just below nominal frequency, i.e. 47Hz on a 50Hz generator or 57Hz on a 60Hz generator. | |
| Air cleaner blocked | Service as necessary | |
| B+ at ECM TB1-10 not present when cranking | No voltage present and fuse F2 is good | Replace ECM |
| B+ to fuel solenoid (K1) terminal BAT does not 'click' when energized | Replace the fuel solenoid if it does not ‘click’; check for blocked fuel line or fuel filter | |
| Blinded air cleaner | Replace element | |
| Charge or Discharged battery | Replace Cell motor Detached or loosened or corroded . . . Repair will not mn battery terminal or revolution Fuse blow Replace Engine will : . . . not start up Improper starter switch Replace Broken lead wire Repair Fuel shortage Supply | |
| Compression failure | Repair engine | |
| Cooling water shortage | Supply Over heat Fan_ belt looseness Adjust Blinded core of radiator Clean Engine thermostat failure Repair Voltmeter failure Replace AVR failure Burned ZNR Contact Burned rotary rectifier distributor or Disconnected rotor wiring our office Burned generator wiring Voltmeter failure Replace AVR _ failure VR failure Contact Rated voltage will not be 7 a Burned rotary rectifier distributor or our office Burned generator wiring Low speed Increase | |
| Cranking voltage is too low to crank the engine. | A. Clean and tighten or replace the positive (+) and negative (–) battery cable connectors and cables at the battery and the set. b. Recharge or replace the battery. Specific gravity for a fully charged battery is approximately 1.260 at 80° F (27° C). c. If the set is in standby service, install a battery charger. d. Replace the engine-driven battery charging alternator if normal battery charging voltage (12 to 14 VDC) is not obtained. | |
| Cranking voltage too low to reach required cranking speed | Measure voltage across battery terminals and starter motor terminal; service as necessary if cable, terminal or relay contact resistance is too high; recharge or replace the battery; replace engine-driven battery charging alternator | |
| Engine lacks power or is unstable | Fuel delivery to the genset is inadequate | Service as necessary |
| Engine speed is low | Improper starter switch Replace | |
| Engine stop by oil failure | Oil_shortage Supply Oil pressure switch failure Replace Blinded _ oil filter Replace element | |
| Engine will not start up | Improper starter Replace Broken lead wire Repair Fuel shortage Supply | |
| Excessive voltage drop on-load | Check transformer secondary winding for short circuited turns. Check speed drop on-load. | |
| Fuse F1 on ECM has blown (no voltage [B+] at ECM TB1-8). | The wire between ECM TB1-8 and starter terminal B1-SW or the wires between TB1-8 – resistor /diode assembly – battery charging alternator may be loose and shorting to ground. | Repair as necessary and replace the fuse with one of the same type and amp rating (20 A). If fuse continues to blow, service or replace the starter, relay K4, or the resistor/diode assembly. |
| High voltage | Check transformer air gap setting - Refer to subsection 4.7.2. | |
| High voltage either on no-load or with load | Check link 1-2 or external hand trimmer leads for continuity. Check speed. | |
| Ignition system, fuel system or other engine malfunction | Service according to the engine service manual | |
| Low engine temperature causes too low a cranking speed for starting | Increase room temperature, plug in, repair or install engine coolant heater; replace the engine oil if it is not of the recommended viscosity for the ambient temperature | |
| Low voltage no-load | Check speed. | |
| Low voltage on-load | Check UFRO setting - Refer to subsection 4.7.1.1. Follow separate excitation procedure to check generator and AVR. | |
| No voltage build-up when starting set | Check link K1i-K2 on AVR terminals Check speed Check residual voltage - Refer to subsection 7.4.4. Follow separate excitation procedure to check generator and AVR. | |
| Speed will not rise | Air in fuel system Remove Blinded fuel filter Replace element | |
| The ECM is faulty. | Push the Run-Stop-Remote switch to Run and check for battery voltage (12 VDC) at ECM TB1-8. Replace ECM if there is no voltage at ECM TB1-8 but 12 VDC at ECM TB1-9. | |
| The Emergency Stop switch has been used. | The switch button is lit. | Pull the Emergency Switch button. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Run. |
| The Run-Stop-Remote switch (S12) or wiring is faulty. | A. Disconnect pin connector J4 from the ECM and check for electrical continuity (zero ohms) between switch terminals 2 and 3 when the switch is in the Run position and between terminals 1 and 2 when it is in the Remote position. Replace the switch if either set of contacts is faulty. b. If the switch works, check for electrical continuity (zero ohms) between J4-6 and J4-7 on the wire harness when the switch is in the Run position and between J4-5 and J4-7 when the switch is in the Remote position. Repair the wire harness if there is no electrical continuity in either position of the switch. | |
| The Time Delay Start/Stop Module (A15) is malfunctioning. | Check for constant B+ at A15 terminal TB1-4. Check for run signal at ECM TB1-5. Voltage at A15 TB1-6 should be at B+ at the end of the start delay period. Check wiring and connections from A15 TB1-6 to ECM TB1-6. | |
| The engine cranks but does not start. | 1. The engine is not getting fuel. a. Open any closed fuel shutoff valve. b. Fill the main fuel supply tank. c. Restore fuel pump prime according to the engine service manual. 2. Fuse F2 on the ECM has blown. Replace fuse with one of the same type and amp rating. If fuse F2 blows again, the wire between ECM TB1-10 and engine block terminal T26, or a wire between terminal T26 and an accessory may be loose or shorting to ground. 3. Fuel solenoid K1 does not energize. | |
| The engine does not crank in RUN mode. | 1. The Run-Stop-Remote switch is at Stop. (The Switch-Off light will be flashing, if provided.) Push the Run-Stop-Remote switch to Remote. 2. The Emergency Stop switch has been used. (The switch button is lit.) Pull the Emergency Switch button. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. 3. A Fault Shutdown is being indicated by one of the red lights on the control panel. Service the set as necessary. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. 4. There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because fuse F3 on the ECM has blown. a. Replace the fuse with one of the same type and amp rating (15 A). b. If fuse F3 blows again, find and repair the fault in the remote control circuit, such as a loose wire that may be shorting to ground or a shorted relay coil or other component. See Section 8 for remote connections. 5. There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because the remote circuit is not functioning properly. Apply 12 VDC to A28-TB1-6. If the engine cranks, find and repair the fault in the remote control circuit. See Section 8 for remote connections. 6. Auxiliary relay board A28 is not functioning properly. Check for misconnections (see Section 8) or loose connections and replace auxiliary relay board A28 if there is 12 VDC at terminal A28-TB1-6 but not at A28-J2-6. 7. Same as Steps 3 through 11 in the RUN mode. See steps 3 through 11 in the preceding RUN mode. | |
| The grounding strap between the control box and the battery negative (–) terminal or the ground wire between the control and engine ground is loose, damaged or missing. | Check for continuity (zero ohms) between the grounding stud on the bottom of the control box and the battery negative (–) terminal. If there is no continuity or the grounding strap is loose or damaged, repair as necessary. | |
| The starter motor or solenoid is malfunctioning. | Push the Run-Stop-Remote switch to Run and check for battery voltage (B+) at starter solenoid terminal SW. Replace the starter motor if there is voltage but the motor does not function. | |
| The wire between ECM TB1-8 and starter solenoid terminal SW is loose, damaged or missing. | Push the Run-Stop-Remote switch to Run and check for battery voltage (12 VDC) at starter solenoid terminal SW. If there is no voltage repair the wiring as necessary. | |
| Unstable voltage either on no-load or with load | Check speed Check stability setting - refer to subsection 4.6. Check speed. |
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.