Ford CSG-6491 Engine

• The standard undesignated fault functions are lights; Engine shuts down immediately, programed to shut down the set when a fault is sensed. Fault 1 is time-delayed while Fault 2 is immediate. FAULT 1 or FAULT 2
• SWITCH OFF lamp flashes
  Fix: Indicates Run/Stop/Remote switch is in the STOP position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/Remote switch to the REMOTE position for automatic starting.
• PRE LO OIL PRES lamp lights. Engine continues to operate
  Fix: Indicates engine oil pressure has dropped to 20 psi (138 kPa). If engine can be stopped, follow procedures in step 5. If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure.
• PRE HI ENGINE TEMP lamp lights. Engine continues to operate
  Fix: Indicates engine has begun to overheat and engine temperature has risen to approximately 205°F (97°C). If engine can be stopped, follow the procedures in step 3. Use the following procedures if generator is powering critical loads and cannot be shut down: a. Check air inlets and outlets and remove any obstructions to airflow. b. Open doors or windows in generator area to increase ventilation. c. Reduce load if possible by turning off non-critical loads.
• LO OIL PRES lamp lights: Engine shuts down
  Fix: Indicates engine oil pressure has dropped to 14 psi (97 kPa). Check oil level and replenish if low. Reset control and restart. Contact an Onan dealer or distributor if oil pressure is not in the range of 35 to 60 psi (241 to 414 kPa)...
• LO FUEL lamp lights: Engine shuts down
  Cause: Indicates engine has run out of fuel.
  Fix: Check fuel level and replenish as required.
• LO FUEL lamp lights: Engine continues to run
  Cause: Indicates gasoline fuel supply is running low.
  Fix: Check fuel supply and replenish if necessary. If set has a combination Gas/Gasoline fuel system, place fuel selector switch in the GAS position to change over to natural gas operation.
• Indicates engine coolant heater is not operating standby mode but is not operating. LO ENG TEMP
  Cause: A. Coolant heater not connected to power supply. b. Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required. c. Contact an Onan dealer or distributor if none of the above.
• HIGH ENG TEMP lamp lights
  Fix: Indicates engine has overheated and engine temperature has risen above 215°F (102°C) or coolant level is low (sets with coolant level sensor). Allow engine to cool down completely before proceeding with the following checks: a. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Check for obstructions to cooling airflow and correct as necessary. c. Check for a slipping fan belt and tighten if loose. d Reset control and restart after locating and correcting problem. Contact an Onan dealer or distributor if none of the above.
• Engine runs and then shuts down
  Cause: Indicates engine has exceeded normal operating speed. Contact an Onan dealer or distributor for service.
• *6. OVERCRANK lamp lights and engine stops cranking. OVERCRANK
  Cause: A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary (see Maintenance section), c. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). d. Check for loose connections in the ignition primary, ignition secondary, or solenoid valve
• *17. Green RUN lamp does not light following engine start-up. GREEN RUN LAMP
  Cause: Indicates possible Start/Disconnect relay failure. Contact an Onan dealer or distributor for assistance.
• *16. No AC output voltage. NO AC OUTPUT VOLTAGE
  Cause: Field breaker is tripped. Reset breaker. Contact an Onan dealer or distributor if voltage buildup causes breaker to trip.
• *15. Engine will not crank. ENGINE WILL NOT CRANK
  Cause: A. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections ... Clean the battery cable terminals and tighten all connections. c. Discharged or defective battery; Recharge or replace the battery. d. Contact an Onan dealer or distributor for assistance if none of the above.
• *14. Remote circuit breaker is tripped. Reset breaker but will not start automatically or from a remote panel (Note: Run/Stop/Remote switch must be in the REMOTE position for automatic or remote starting). REMOTE CIRCUIT BREAKER

Compiled from service & troubleshooting documentation across every generator set that uses the Ford CSG-6491.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.