There is NO pilot flame....only flame that ignites is the MAIN Flame
When switch is turned ON....do you hear a 'click, click, click' ??
Do you see electrode sparking?
Got to have sparking before flame can light off
DC Voltage comes from on/off switch to a junction box on backside of water heater tank
From junction box to the set of t-stat (under that Push To Reset Cover)
Right side is for the propane...Top T-stat (Hi Temp) has a manual reset button
DC goes to the top t-stat then down connecting wire to bottom t-stat
This is dual sets of t-stats (120VAC for electric and 12VDC for propane)
NOTE....burnt thru wire on the 120VAC. Similar could be your issue with the 12VDC
From t-stats to circuit board....backside of water heater tank OR mounted close by
From circuit board....high voltage to spark electrode and 12V DC to gas valve solenoids (BOTH have to work for gas valve to open)---DC on solenoids for only 6-8 seconds while spark electrode is firing.
12VDC wiring.....using a voltmeter follow the DC circuit from switch to gas valve