I agree with Chuckster. I've seen several limit switches with corroded contacts that won't provide current to allow the furnace to operate. So, maybe it is, probably it isn't, but stranger things have happened, so always check and never assume......
Here is an excellent Atwood Furnace Troubleshooting Guide:
http://bryantrv.com/docs2/docs/hflamefurn04.pdf
ADDED: Here is another good source of information about RV furnace troubleshooting:
https://www.rvda.org/App_Themes/RVDA...Tech_FINAL.pdf
Heck, it even has pictures !!!!! LOL
Good Luck and keep us posted on what you find.