Suburban NT30sp furnace valve

[Vinny72]

I have discovered that the furnace valve is letting gas by causing a strong odour. Upon taking furnace out and apart I can hear the valve opening and closing every 20-30 seconds. Is this a problem with the valve itself, the board, or the thermocouple? Thanks in advance.

[Vinny72]

Sooooo.... It's the board?

[Old-Biscuit]

SEQUENCE OF NORMAL OPERATION
The electronic ignition system is made up of three main parts: the module board, the electrode assembly, and the electrode wire. The module board is the brain of the electronic ignition system and it has several functions.
1.When the blower reaches approximately 75% of the normal rpm and sufficient airflow is established, the sail switch engages and completes a 12-volt circuit through the limit switch to the module board.
(NOTE: Low voltage power supply will not provide
sufficient motor rpm to engage the sail switch.)
2.After a 12-18 second delay, 12-volt current will pass through the module board to the solenoid valve. The current to the valve opens it and allows gas to the main burner, simultaneously, the module board sends high voltage through the electrode wire to the electrode assembly. The voltage seeks a ground between electrode and ground probe and a spark occurs. The spark then ignites the main burner.
3.The module board also performs the lockout function in cases where the spark fails to light the burner. When lockout occurs, the spark stops, the voltage from the module board to the gas valve is discontinued, and the valve closes. The unit will remain in lockout and the blower will continue to run until the thermostat is turned off. Turning the thermostat off disengages the lockout function of the module board. After the blower has stopped, the ignition sequence can be started again.

Manual

Gas valve should NOT be opening/closing.
Opens when spark occurs, stays open IF main flame is proven otherwise it trips closed (no power) until 'lock-out' is reset.

Module board should not be applying power to gas valve repeatedly.
Furnace doesn't use a 'thermocouple'...the spark electrode is used to light off main flame AND to prove main flame lit.