I have a Lennox G40 series furnace and the gas valve will not open. After it does the preliminary start up I get 27V to the gas valve, but only for about half a second. Periodically the LEDs will state that there is open primary/ secondary limits, but if I jumper those out the problem persists. And by periodically I mean 1 out of 5 times trying to start the furnace from power off to running. The LEDs typically just synchronized fast flash saying there is a call for heat. Does it make sense for the limit switch to be the problem?