The terminal at the PCB for the ignitor should be squeezed a little with a pair of needle nosed pliers to make a really tight connection.
The flame is sensed by the ignitor itself. The flame causes a low resistance path from ground (the metal tube where the gas exits as a flame) to the ignitor. The circuitry is designed to send a high voltage pulse to the ignitor, then switches to a low current sensing circuit. When the spark causes a flame, the flame lowers the resistance of the ignitor just enough that a high sensitivity circuit can measure those few hundred microamps of current flowing so it keeps the propane valve ON. Otherwise, it turns it off, resets everything, then tries again.
I believe it gives it 3-5 tries, with a wait period between tries, before it gives up and throws a NO FL code. Your book should tell you.
