Atwood FA7912D Not Staying Lit

[northbound6]

Hi all,

On the road and in a bind. My 93’ truck camper has a Atwood FA7912D furnace. Has worked perfect the last 6 days and all of the sudden it lights but then goes out. I read the original owner manual and understand that since the fan comes on and ignites it means the thermostat, blower motor and sail switch are likely okay. I actually replaced sail switch and blower motor last year. Since it’s not staying lit I’m thinking the thermocouple but wondering what else it could be and how to test.

Really appreciate the help!!!

Original manual https://www.wohnkabinencenter.de/manuals/heizung_woka.pdf

[Old-Biscuit]

Spark electrode.........

It has dual purpose
*Provide High Voltage spark for ignition
*return path for Flame Sensing current......just a few milliamps

Spark gap....... 1/8"
Ceramic insulator........no cracks
High tension wire.....solid/clean connection
Electrode........CLEAN (soot/carbon will inhibit return of flame sensing)