Cummins/Onan KTTA-50-G1 Engine

How to read your Cummins/Onan engine serial & model number →

• The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run — The standard undesignated fault functions are programmed to shut down the set when a fault is sensed. Fault 1 is time delayed while Fault 2 is immediate. The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay 12
• SWITCH OFF lamp flashes — Indicates Run-Stop-Remote switch is in the Stop position which will prevent automatic starting 8
  Cause: Run-Stop-Remote switch is in the Stop position
  Fix: Moving the Run-Stop-Remote switch to the Remote position will stop the lamp flashing and enable automatic starting.
• PRE-LO OIL PRES lamp lights. Engine continues to operate — Indicates engine oil pressure has dropped to 20 psi (138 kPa) 4
  Cause: Engine oil pressure has dropped to 20 psi (138 kPa)
  Fix: If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure. If engine can be stopped, follow procedure in step 5.
• PRE-HI ENGINE TEMP lamp lights. Engine continues to operate — Indicates engine has begun to overheat and engine temperature has risen to approximately 205° F (97°C) 2
  Fix: If generator is powering non-critical and critical loads, and cannot be shut down: reduce load if possible by turning off non-critical loads; check air inlets and outlets and remove any obstructions to airflow; open doors or windows in generator area to increase ventilation. If engine can be stopped, follow procedure in Step 3.
• OVERCRANK lamp lights and engine stops cranking — Or: Engine runs, shuts down, and LO OIL PRES lamp lights — Indicates possible fuel system problem 6
  Cause: Possible fuel system problem
  Fix: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required; check for dirty fuel filter and replace if necessary (see MAINTENANCE section); check for dirty or plugged air filter and replace if necessary (see MAINTENANCE section); refer to step 5; reset the control and restart after correcting the problem; contact your distributor for service if none of the above applies.
• No AC output voltage (Note: If unit is equipped with an excitation breaker located on back side of output box, near regulator box, confirm it is at ON position) 16
  Cause: Voltage regulator is inoperative
  Fix: Refer to Initial Start and Checks, and Adjustments sections of your Installation Manual for voltage check and adjustment procedures; contact your distributor if voltage build-up is still a problem.
• LO OIL PRES lamp lights. Engine shuts down — Indicates engine oil pressure has dropped to 14 psi (97 kPa) 5
  Cause: Engine oil pressure has dropped to 14 psi (97 kPa)
  Fix: Check oil level, replenish as necessary; check oil lines and filters for leaks, repair as required; reset control and restart; contact your distributor if oil pressure is not in the range of 50 to 70 psi (345 to 483 kPa).
• LO FUEL lamp lights. Engine shuts down and LO OIL PRES lamp lights — Indicates engine has run out of fuel 10
  Cause: Engine has run out of fuel
  Fix: Check fuel level and replenish as required.
• LO FUEL lamp lights. Engine continues to run — Indicates diesel fuel supply is running low 9
  Cause: Diesel fuel supply is running low
  Fix: Check fuel supply and replenish as required.
• LO ENG TEMP lamp lights. Set is in standby mode but is not operating — Indicates engine coolant heater is not operating or is not circulating coolant (lamp lights when engine coolant temperature is 70° F (21° C) or lower; since the lamp goes out after the engine warms up, there should be no cause for alarm if it remains lighted during initial generator set operation) 11
  Cause: Engine coolant heater is not operating or is not circulating coolant
  Fix: Check for the following conditions: coolant heater not connected to power supply, check for blown fuse or disconnected heater cord and correct as required; check for low coolant level and replenish if required, look for possible coolant leakage points and repair as required; contact your distributor if none of the above applies.
• HI ENG TEMP lamp lights. Engine shuts down — Indicates engine has overheated (engine temperature has risen above 215° F/102° C) or coolant level is low (sets with coolant level sensor) 3
  Cause: Engine has overheated (engine temperature has risen above 215° F/102° C); coolant level is low (sets with coolant level sensor)
  Fix: Allow engine to cool down completely before proceeding: check coolant level and replenish if low, look for possible coolant leakage points and repair if necessary; check for obstructions to cooling airflow and correct as necessary; check for a slipping fan belt, tighten if loose; reset control and restart after locating and correcting problem; contact your distributor if none of the above applies.
• Green RUN lamp lights following engine start-up — Indicates all engine systems are normal 1
  Fix: No corrective action required.
• Green RUN lamp does not light following engine start-up — Indicates possible Start/Disconnect relay failure 17
  Cause: Possible Start/Disconnect relay failure
  Fix: Contact your distributor for assistance.
• Fault lamp lights but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits 13
  Cause: The monitor board or a sensor may be at fault
  Fix: Contact your distributor for service.
• Engine will not crank — Indicates possible fault with control or starting system 15
  Cause: Fault lamp on; poor battery cable connections; discharged or defective battery
  Fix: Correct fault and reset control; clean the battery cable terminals and tighten all connections; recharge or replace the battery; contact your distributor for assistance if none of the above applies.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan KTTA-50-G1.

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.