The Mobile Digital is a generator-set controller. It is used on generator sets from Generac, including the MMG25FHI, MMG35FH, MMG45FHK and MMG55FH.
| Symptom | Cause | Remedy |
|---|---|---|
| High Coolant Temperature Shut Down | Check coolant level in overflow jug. | Restart engine and read coolant temperature to verify high coolant temperature shutdown. Stop engine immediately if coolant temperature is 230°F (110°C) or more. Allow engine to cool. Add coolant to overflow jug if it is low and then check coolant level in radiator. Open front hood to access the radiator cap. Add coolant until it is 3/4 in. (1.9 cm) below filler neck. Secure radiator cap back into its original position. Check radiator shroud and ducting for blockage and remove any foreign matter. Inspect coolant hoses, engine block and water pump for visible leaks. Check the tension of the water pump belt. If no other problems are found, remove the load on the generator and restart the engine. Check the coolant temperature and shut the engine down immediately if it starts to overheat. |
| Low Coolant Level Shut Down | Allow engine to cool. Confirm unit is level to ensure an accurate reading. | Check coolant level in radiator. Open the front hood to access the radiator cap. Add coolant until it is 3/4 in. (1.9 cm) below filler neck. Secure the radiator cap back into its original position. Inspect coolant hoses, engine block and water pump for visible leaks. Check engine oil to verify no coolant has mixed with it. Oil will appear milky if coolant is present. |
| Low Fuel Level Shut Down | Check fuel level on LCD display. Check for fuel tank leaks. The engine controller will shut the engine down when there is five percent of fuel remaining in the tank. | Check the fuel level sender and connecting wiring for damage. To check for continuity between sender and engine controller, remove the appropriate bolts from control panel to access the inside of the control box. Consult the appropriate DC wiring diagram for the proper path between the engine controller and the fuel level sender. |
| Low Oil Pressure Shut Down | Check the engine oil level with the dipstick. Add oil if required. Inspect engine for oil leaks. | If oil level is good, restart the unit and verify loss of oil pressure. Shut the engine down immediately if the oil pressure value does not read 5 psi (34 kPa) within five seconds. Check oil pressure sender. To identify corrective action, refer to the troubleshooting section of the engine operator’s manual provided with the unit. |
| Overcrank Shut Down | Check fuel level in tank. Check for proper operation of the fuel pump. Check air filter for blockage. | If engine will not start, consult the engine operation and maintenance manual. |
| Overspeed or Underspeed Shut Down | Disconnect all loads and restart generator. Read the frequency (Hz) on the display. With no loads on the generator, the frequency should read 60.0 Hz. | If frequency is above or below 60.0 Hz, the engine speed needs to be adjusted. See the engine manual for throttle adjustments on mechanical governed units and see the electronic governor manual for electronically controlled units. |
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.