TOA Electronics P0055-DRG - Manual (Page 15)

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NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
TROUBLESHOOTING THE ELECTRONIC IGNITION SYSTEM
N ote: Before troubleshooting, be sure that the appliance main line gas shut-off valve, the gas control valve and the wall switch are in
the “ON” position.
Important: “ON/OFF” switch must be “OFF” before performing continuity test. Adjust multimeter to the ohm setting when performing continuity tests.
Important: Valve system troubleshooting should only be accomplished by a qualified service technician.
Confirm 24Vac output from transformer (red and blue leads). If no, then replace
transformer.
Note: Before replacing transformer check wiring for loose connections or broken wires
and repair as needed. Turn off power before replacing transformer.
Disconnect the two black wires from the two red wires attached to the limit switch and
transformer (label wires for correct reattachment). Test “ON/OFF” wall switch for
continuity with a multimeter. If continuity is not indicated, switch is defective and must
be replaced.
Note: Before replacing “ON/OFF” switch be sure to check switch wiring for loose
connections or broken wires and repair as needed.
Reset the limit switch button. If still not working, isolate the limit switch in the same manner
as the “ON/OFF” switch (label wires for correct reattachment) and test for continuity with
a multimeter. If continuity is not indicated, switch is defective and must be replaced.
If reading is not 24V at “TH” and “TR” terminals on ignition control, replace ignition
control module.
Check for availability of gas at control. Check that manual valve upstream of gas control
and manual valve on gas control are in the full “ON” position. Check for plugged pilot
orifice or plugged pilot tubing. Also check pilot key adjustment at gas control valve.
Confirm 24Vac at gas valve terminals “C” and “P” of the gas valve. If yes, valve is OK. If
no voltage, check the wiring. If wiring tests OK, check ignition control module.
Confirm 24Vac at “PV” and “PV/MV” on ignition control module. If no, replace the ignition
control.
Check if pilot line and pilot orifice are plugged. Clean or replace as necessary. Adjust pilot
flame if necessary.
Confirm that the igniter is sparking at the pilot assembly when the “ON/OFF” switch is
activated. If not, undertake the following steps:
With “ON/OFF” switch “OFF,” remove wire at “TR” terminal at the ignition control module.
Disconnect the electrode wire “IGN” at the ignition control. Connect one end of a jumper
wire to the metal blade of a small screwdriver. Attach the other end of the jumper wire to
any metal part of the chassis. Reconnect the “TR” terminal. Position end of metal blade
approximately
¹⁄₈" (3 mm) from the “IGN” terminal. Activate the “ON/OFF” switch.
Sparking should occur between the “IGN” terminal and screwdriver blade. If sparking
does occur, the ignition control module is OK, but either the electrode wire of the igniter
is faulty and the pilot and electrode assembly should be replaced.
Electrode tip needs to be realigned to correct location. ³⁄₃₂" to ¹⁄₈" (2 – 3 mm) gap between
electrode tip and pilot hood is desired.
Pilot and electrode igniter must be properly aligned so that the pilot flame impinges the
top
³⁄₄" (19 mm) of the electrode igniter. The electrode igniter must be pushed all the way
into the pilot bracket. Adjust pilot flame if necessary.
Check main burner orifice(s) for stoppage. Clean or replace.
Check for 24 volts at gas operator terminals “M” and “C.” If there is a 24V reading and the
burner does not come on, the valve operator is defective and the gas valve must be
replaced.
Adjust pilot flame and/or check location of electrode igniter.
SYMPTOM CORRECTIVE ACTION
1. No spark and no pilot gas.
2. Spark but no pilot gas
(no solenoid valve click).
3. Spark but no pilot gas
(solenoid valve click).
4. Pilot gas available, but
pilot does not light
(solenoid click).
5. Pilot burning but main
burners will not come on.
Note: Wait at least 90
seconds after pilot lights
before doing the checkout
for possible causes.
6. Burners come “ON” but go
“OFF.”
A. Faulty transformer.
B. “ON/OFF” switch defective.
C. Limit switch defective.
D. Ignition control module defective.
A. No gas supplied to pilot valve.
B. Faulty gas valve.
C. Ignition control module defective.
A. Gas supply to pilot restricted.
A. Ignition control or igniter
defective.
B. Sparking, but not at proper
location.
A. Low pilot flame or improper
alignment of electrode igniter in
pilot flame.
B. Burner orifice(s) plugged.
C. Gas valve defective.
A. Low pilot flame or electrode
igniter not correctly positioned.
POSSIBLE CAUSES