We noticed that the furnace would not work at all last november 2015 when hooked to campground power (no blower or ignition) . Subsequently,After being left at the shop for 2 months, 8 hours of service was done to the camper; apparently a major re-wire. When we went for our first Spring "shakeout" overnighter in March, we found that while the blower fan worked, the ignitor would not light the furnace. Last weekend I followed steps described elsewhere on these forums to clear out the gas lines. I was able to get the furnace to ignite once, and it actually burned for 2 hours using battery power. When I tried to ignite again after 2 hours off, there would be a momentary burst of heat from the exhaust vent but no ignition. One thing I observed was that a lit burner on the stove would extinguish when the ignitor clicked. When I was able to get a Suburban furnace expert on the phone at the local CW shop, he informed me that it sounded like a bad regulator. I was able to find an exact replacement Fairview Model GR 9959 on Amazon which was delivered same day. The swap out took me an hour (since I was not familiar with the process) to loosen the fittings, properly apply the yellow PTFE thread tape, and soap bubble test the reconnected fittings for gas leaks (there was leakage on the outlet side which I remedied by tightening another turn). We opened the PU this morning. On battery power the ignitor caught the burner 1st try and the furnace ran for 1 hour. We turned the furnace off for 1 hour, and success! again ignited 1st try.
I now have confidence in my ability to do this repair in 30 minutes and plan to carry along a spare 2 stage LP pressure regulator in the camper during the cold months. This new camper has only been in use for 25 months. The regulators should last 10 years but my experience shows only 2 years. So while sail switches and circuit boards may be involved, in this case a $26 part easily replaced by the owner was the cure.
P.S. I posted this by mistake to the motorhomes forum. I will attempt to copy to the popups forum. However, do remember to consider the regulator.