Page last updated Sep 15, 2026 @ 11:06pm
300-0679
300-C679
Replacement 12v Engine Control Monitor
Replacement for Onan Part Number 300-0679 and 300-C679 12V Engine Control Monitor.
Built in the USA and backed by a 2-year warranty.
Features and Instructions:
This product is designed to replace Onan part number 300-0679 in 12-volt systems.
This board is reset by turning off the RUN/STOP switch.
The keying slots in the circuit board allow it to be plugged into a 12-volt system only and also prevent improper insertion into the connector. Take care to align the slots and then press the board down until it is fully seated into the connector.
The adjustment range of the OVERCRANK alarm time delay is 20 to 75 seconds. Adjust the OVERCRANK DELAY (R1) as needed, turning clockwise to increase the delay. The adjustment is clearly marked.
The adjustment range of the LOW OIL PRESSURE alarm time delay is 8 to 30 seconds. Adjust the LO OIL P. DELAY (R5) as needed, turning clockwise to increase the delay. The adjustment is clearly marked. Keeping the delay as short as possible without false tripping will result in maximum engine protection.
The IGN/FUEL output (pin 7) and the ALARM output (pin 8) are each rated at 5 Amps (relay rated at 10 Amps) regardless of system voltage. Overloads on these circuits can cause damage to the relay contacts and circuit board traces on original Onan boards. Severe damage to traces renders the circuit board non-repairable.
This product has a special fusible link that acts as a fuse in case of an overload. This feature helps to prevent damage and allows the board to be repaired instead of discarded.
All sensor inputs have filters to improve noise immunity and help prevent false alarms.
Older Onan boards have tin-plated contact fingers on one side only. Later Onan boards have gold plated contacts on both sides of the board which ensures a more reliable connection. This product also has gold plated contacts on both sides.
Item Number: 300-0679
Price: $450
Price last updated 9/14/2026
Shipping Weight: 2 lbs.
This item normally ships in approximately 3 days or less.
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