I have a Day & night model 588, the ignition circuit board LED indicates a fault #8 (internal control fault). Are there voltage checks to confirm that the circuit board needs replacement.

Looks like circuit board.

8 Flashes Internal Control Fault •

You might check all the grounds from the furnace back to the main electric panel.

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Originally Posted by hvac1000

Looks like circuit board.

8 Flashes Internal Control Fault •

You might check all the grounds from the furnace back to the main electric panel.

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Thanks! I will check the ground connections. If this does not work I will need a replacement circuit board. Do you know what the replacement circuit board is for the original 48SS500177 board.

I find no listing for that part number.

Example of numbers below

http://heatcoolparts.com/webpages/Ca...nControls.html