Magnum MTT20 troubleshooting: 9 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Magnum MTT20 — full specs, parts & maintenance.
| Symptom | Remedy |
|---|---|
| Mast light is too hot. | Allow light to cool 10-15 minutes before restarting. |
| Faulty bulb connection. | Check that the bulb is tight in the socket. |
| Bulb broken. | Check for broken arc tube or outer bulb jacket, broken or loose components in bulb envelope or blackening/deposits inside tube. |
| Mast lights off and ballast indicators on control panel are off. | 1. Check the connections inside the control box and inside each ballast box. 2. Generator output incorrect. Check the incoming voltage to the ballast by checking the available voltage on the GFCI receptacle. Incoming voltage should be 120V +/- 5V. If voltage is incorrect, the engine speed may need to be adjusted or generator may require service. 3. Low transformer output. The voltage from the transformer should read approximately 400VAC as the light 'strikes' (induces an arc), then drop and slowly rise back up to stabilize at 240-260VAC. On quick disconnect models, measure across the junction box terminals when the light is unplugged. On hard wired models, remove the mast junction box cover and insert the wire probes into the connector blocks for the light and ground. If proper voltage is not achieved, perform capacitor check to determine if the capacitor or coil needs to be replaced. |
| Mast lights on but the light output is low. | 1. Fixture and/or lens is dirty. Clean reflective surface inside fixture and both inside and outside surface of glass lens. Use mild soap and water to clean lens. Other chemicals may have an adverse effect on the glass. 2. Bulb worn due to normal use. Replace bulb. 3. Check the mast coil cord, mast junction box and mast light connections. 4. Generator output incorrect. Check the incoming voltage to the ballast. Incoming voltage should be 120V +/- 5V. If the voltage is incorrect, the engine speed may need to be adjusted or the generator may require service. 5. Low transformer output. The voltage from the transformer should read approximately 400VAC as the light 'strikes' (induces an arc), then drop and slowly rise back up to stabilize at 240-260VAC. On quick disconnect models, measure across the junction box terminals when the light is unplugged. On hard wired models, remove the mast junction box cover and insert the wire probes into the connector blocks for the light and ground. If proper voltage is not achieved, perform capacitor check to determine if the capacitor or coil needs to be replaced. |
| LOW OIL PRESSURE SHUTDOWN | 1. Check the level of the engine oil with the dipstick. The engine controller will shut the engine down when the oil pressure is less than 20 psi (138 kPa). Add oil if required. 2. Visually inspect the engine for oil leaks. 3. If the oil level is good, restart the unit and verify the loss of oil pressure. Shut the engine down immediately if the oil pressure value does not read 5 psi (34 kPa) within five seconds. 4. Check the oil pressure sender. To identify corrective action, refer to the troubleshooting section of the engine operator’s manual provided with the unit. |
| HIGH COOLANT TEMPERATURE SHUTDOWN | 1. Check the coolant level in the overflow jug. 2. Restart the engine and read the coolant temperature to verify a high coolant temperature shutdown. Stop the engine immediately if the coolant temperature is 230°F (110°C) or more. 3. ALLOW THE ENGINE TO COOL. Add coolant to the overflow jug if it is low and then check the level of coolant in the radiator. To access the radiator cap, you must remove the access panel from the top of the enclosure directly above the radiator. Add coolant until it is 3/4 in. (1.9 cm) below the filler neck. Secure the radiator cap back and access panel into their original position. 4. Check the radiator shroud and ducting for blockage and remove any foreign matter. 5.Inspect coolant hoses, engine block and water pump for visible leaks. 6. Check the tension of the serpentine drive belt for the water pump. 7. 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. For additional information on engine overheating, refer to the engine operator’s manual. |
| OVERCRANK SHUTDOWN | 1. Check the fuel level in the tank. 2. Check for proper operation of the fuel pump. 3. Check the air filter for blockage. 4. If the engine will not start, refer to the engine operator’s manual for additional information on trouble-shooting starting problems. |
| OVERSPEED OR UNDERSPEED SHUTDOWN | 1. Disconnect all loads and restart the unit. Read the frequency (Hz) on the LCD display. With no loads on the generator, the frequency should read 60.0 Hz. 2. If the frequency is above or below 60.0 Hz, the engine speed will have to be adjusted. Refer to the engine operator’s manual for throttle adjustments on mechanical governed units and see the electronic governor manual for electronically controlled units. 3. If problems persist, contact Magnum Power Products LLC Technical Service at 1-800-926-9768 for assistance. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.