There is no Low Voltage on this unit, there is only high (120v) and higher (5,000 VDC) at the output terminals. This is not a re-ignition type ignitor, meaning that all burners spark when only one valve is turned. Be sure all of your brner switches are oriented securely on the valve stems.
One of your individual burner switches is likeely bad, causing power to the 2 main leads on the spark module. Your job is to find and replace the offending switch, which should be relatively easy if you turn off power to the range and unplug each switch to check for resistance. This usually occurs when grease gets into a switch and shorts the contacts, but can be a mechanical failure as well within the switch. Since the ignitor spark is only seeking a path back to ground, any hairline crack in the ceramic ignitor electrode can re-direct the spark to the main top without lighting the burner.