The VR3 automatic voltage regulator is a generator-set controller. It is used on generator sets from Caterpillar, including the SR4.
| Symptom | Cause | Remedy |
|---|---|---|
| Overcrank Protection - If the engine fails to start in a preprogrammed amount of time, the ECM will halt the starting sequence and flash the Overcrank LED. | Another attempt to start the engine cannot be made without first going to the offlreset position on the engine control switch (ECS). | |
| The engine will be shutdown by means of the air and fuel control and a diagnostic code will be displayed. | If the ECM loses its magnetic pickup signal | Refer to the Service Manual Module SENR3535, which is included in the Service Manual SENR7958 for diagnostic fault codes. |
| The engine will be shutdown by means of the fuel control and a diagnostic code will be displayed. | If the signal from the engine mounted oil pressure/temperature transducer module is lost or unreadable | Refer to the Service Manual Module SENR3535, which is included in the Service Manual SENR7958 for programming instructions and diagnostic fault codes. |
| The engine will be shutdown by means of the fuel control and the Low Oil Pressure LED will flash. | If the engine oil pressure drops below the low oil pressure setpoint | |
| The engine will shutdown by means of the fuel control and the High Coolant Temperature LED will flash. | If the engine coolant temperature exceeds the high coolant temperature setpoint | |
| The engine will shutdown by means of the fuel control and the Overspeed LED will flash. | If the engine speed exceeds the overspeed setpoint | Lower the overspeed setpoint to 75% of its original value while the overspeed verify switch is depressed. This allows the overspeed circuit to be tested while a generator set is operating at rated speed. |
| The red fault shutdown indicator flashes when the GSC detects a fault that is a shutdown condition. | Refer to SENR5809 for fault code descriptions. |
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.