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If ALL safety switches are closed, the burner controller module (BCM) will start the
burner fan motor (BCM terminal #8).
The BCM (burner controller module) waits 10-seconds to allow the blower motor to get up
to speed, and then checks that the burner fan combustion air switch (BCM terminal #6)
circuit is closed. If this circuit is open during the drying cycle, the “Air Failure” L.E.D.
(light emitting diode) will light. The gas valve will close, and a “HEATER FAULT”
message will be displayed.
In order to prevent this air switch from being jumped out, the BCM (burner controller
module) checks to insure that this circuit is open prior to start-up, then “SYSTEM
UNSAFE” L.E.D. (light emitting diode) will light.
If the air flow switch closes after the burner fan is turned on, the pilot solenoid valve (BCM
terminal #3) is opened for 10-seconds and a spark is produced (BCM terminal #4) by the
burner spark plug, igniting the pilot flame.
The flame rod, which extends into the pilot flame, has 300 VAC on it from the (BCM
terminal #S1). The flame lets the current flow from the flame rod to ground, which is then
converted to 3 volts to 11 volts DC by the BCM (burner controller module). The “flame
signal” L.E.D. (light emitting diode) on the BCM lights up.
The spark plug will turn off 1.5-seconds after the pilot flame is detected. If the pilot flame
should fail during the 10-seconds period that the pilot solenoid is open. The BCM (burner
controller module) will reenergize the spark. If the pilot flame is not established at the end
of this 10-second period, the system will lock out and the “FLAME FAILURE” L.E.D.
(light emitting diode) will light.
The 10-second period when the pilot solenoid opens and a spark is produced is called the
trial-for-ignition (TFI) time. It is selected at either 5-seconds or 10-seconds by a dip switch
located on the back cover of the BCM (burner controller module).
The 3 volt DC to 11 volt DC signal from the flame rod to the BCM (burner controller
module) can be measured by;
(a) Closing the manual shut-off valve in the main gas line to the burner. Leave the pilot manual
valve open.
(b) Push the Test and Reset Button on the cover of the burner control module (BCM) in to the
“test” position.
(c) Start a drying cycle... the burner controller module (BCM) will halt the ignition sequence
after the pilot is ignited. The pilot flame should be about the size of a tennis ball and
should make the flame sensor red hot.
(d) Insert the positive probe of a DC voltmeter in to the “flame signal” port on the cover of the
burner controller module (BCM). Connect the negative probe to ground.
(e) If signal is less than 3 volts DC, then the pilot may be too small or too large, there may
be a wiring connection between the flame rod and BCM (burner controller module), the
flame rod may be dirty, (wash it with soap and water) defective, or the grounding may
be faulty.