The Modbus RTU communication protocol. is a generator-set controller. It is used on generator sets from Kohler, including the Digital and Digital 550.
Also fitted to: Kohler Microprocessor-Plus, 16-Light.
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| Blinking Fast (1 1/2 Hz) | Governor controller is powered and an engine speed signal is being detected. If the engine is not running, this indicates electrical noise on the speed signal wires | ||
| Blinking Slow (1/2 Hz) | Governor controller is powered, but not sensing a speed signal. OK if engine is not running. If the engine is running, this indicates a fault with the speed signal | ||
| E0 | Controller memory failure | Replace governor controller. | |
| E1 | Loss of remote speed potentiometer signal | ||
| E2 | Overspeed detected. Governor controller must be turned off and reset to allow an engine restart | ||
| E3 | Actuator drive overcurrent detected | Check wiring. Check actuator loading and linkage. | |
| F1 | Blown F1 fuse (remote annunciator: 3 amp) | ||
| F2 | Blown F2 fuse (controller: 3 amp) | Battery connections reversed; shorted DC supply to indicator panel circuit board; shorted controller circuit board | Replace blown fuses and resume operation; if the fuse blows again, use the chart to identify the faulty component(s) |
| F3 | Blown F3 fuse (engine and accessories: 15 amp) | Defective engine electrical (wire 70) components; defective panel lamps or engine gauges; defective dry contact kit, audio/visual alarm kit, and other accessories connected to TB1-42A | Replace blown fuses and resume operation; if the fuse blows again, use the chart to identify the faulty component(s) |
| ON and Not Blinking | Governor controller is powered and is malfunctioning | Replace governor controller. | |
| Off | Governor controller is either not currently powered or is being reverse powered | Check polarity of supplied power. If correctly powered, governor controller is malfunctioning. |
| Symptom | Cause | Remedy |
|---|---|---|
| Alarm horn will not silence using alarm horn silence switch | Improper operation sequence | Place generator set master switch in the AUTO position before placing the alarm horn silence switch in the SILENCE position; see generator set operation manual |
| All lamps remain on | Ground fault from accessories connected to TB1 terminal strip | Disconnect and test each connection; see wiring diagram manual |
| Aux. lamp goes on with generator set master switch in RUN or AUTO position | Defective generator set master switch | Check switch contacts with an ohmmeter; if switch is defective, replace generator set master switch (lamp circuit board) |
| Controller instrumentation not functioning properly | Loose input or component lead connection at AC fuse terminal block (TB3) or at component | Secure the connection |
| Engine cranks but will not start | Fuel low | Add fuel |
| Engine does not reach set speed | Improper Proportional, Integral, and Derivative (PID) tuning values. | Check and adjust the PID values. |
| Engine does not start | Actuator leads not connected or shorted. | Check and correct actuator wiring. |
| Engine does not track speed setting changes | Is the LED decimal point flashing (load share model)? | If yes, enter password. |
| Engine overspeeds at startup | The proportional value is too low. | Increase the proportional value. |
| Engine starts and runs, but overcrank lamp flashes | Open speed sensor circuit (wire 2 black, wire 16 white, wire 24 red between P1 connector and speed sensor) | Repair circuit; replace speed sensor; replace main control board |
| Engine takes too long to reach the set speed | Improper PID tuning values. | Check and adjust the PID values. |
| Engine will not crank with generator set master switch in RUN position | Battery not fully charged | Charge battery and attempt restart; if engine will not crank, continue troubleshooting sequence |
| Excessive smoke at startup | Improper PID tuning values. | Check and adjust the PID values. |
| Indicator panel circuit board not functioning or not functioning properly (generator set master switch only) | Not In Auto lamp does not light when the master switch is in OFF/RESET position | Troubleshoot indicator panel circuit board and wiring; see Figure 3-21 and Figure 3-22 |
| LED display does not light up when the governor controller is powered | BAT+ and BAT-- leads are reversed. | Check and correct wiring. |
| Lamp circuit board not functioning or not functioning properly (fault lamps and alarm horn only) | All lamps do not light when lamp test button pressed | Replace main circuit board; replace ribbon connector; replace lamp circuit board |
| OVERCRANK shutdown fails to function | Speed sensor and related circuitry faulty | Check the speed sensor and related circuitry; see Section 3.6.5, Controller Speed Sensor Circuitry, and Section 6.18, Speed Sensor Test |
| Remote accessories (audiovisual alarm, remote annunciator, dry contact kits, etc.) will not operate | Correct voltage not detected at the TB1 terminal strip test point | Test for output voltage at the TB1 terminal strip; see Figure 3-25 and Figure 3-26 for test point connections |
| Slow response to load changes | Gain value set too low. | |
| System ready lamp does not light | Defective generator set master switch | If engine/generator set checks out okay, replace generator set master switch (lamp circuit board); check switch contacts with an ohmmeter; if switch is defective, replace generator set master switch (lamp circuit board) |
| Unable to modify parameters | The parameter's value is the maximum value allowed. | Enter acceptable value. |
| Unit will not crank when 3-4 contacts are closed (remote starting) and generator set master switch in AUTO position | Defective generator set master switch | Connect jumper wire between terminals 3-4; if unit cranks replace generator set master switch (lamp circuit board); see wiring diagram manual |
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.