T-M50 / T-M50 ASME Service manual
Ver. 1.05
39
CONFIDENTIAL
Error Code
Diagnosis
Checkpoint
101
8 Check if there is dust and lint in burner and heat exchanger, when the water
heater has been installed in laundry room.
9 Check if there is grease and dirt in burner and fan motor, when the water
heater has been installed in restaurant.
10 Check the manifold pressure in the water heater.
Error Code
Malfunction description
Cancellation method
Ignition failure
Turn off the power or water supply
Diagnosis
Checkpoint
1 Check gas supply and inlet gas pressure (Refer to section 1)
2 Check the igniter (Refer to section 10-18)
Visual inspection: connection/breakage of wires and/or observed weak
spark.
[1] Cracks/soot on igniter rod
[2] Improper gap between burner & igniter rod
Normal gap: 0.16" (4mm)
[3] Fault of Left and/or Right PCB
Normal: 90 to 110 VAC at #7 (purple-purple) (during ignition)
B
3 Fault of Left and/or Right PCB
[1] No voltage to main gas solenoid valve (MV)
Normal: 78 to 100 VDC between COM (blue) & #3 (light blue)
[2] No voltage to gas solenoid valve (SV
2
)
Normal: 78 to 100 VDC between COM (blue) & #53 (orange)
[3] No voltage to gas proportional valve (VG
0
)
Normal: 1 to 15 VDC between white & red
C
H1
4 Gas solenoid valve fault
[1] Main gas solenoid valve (MV) fault
Normal: 0.9 to 1.3 kΩ between COM (blue) & #3 (light blue)
[2] Gas solenoid valve (SV
2
) fault
Normal: 1.3 to 1.9 kΩ between COM (blue) & #53 (orange)
[3] Gas proportional valve (VG
0
) fault
Normal: 1 to 15 VDC between white & red
C
H1
5 Disconnected/damaged O.H.C.F.
(Refer to section 10-12)
Visual inspection: connection/breakage of wires.
Normal: 1 Ω or less between blue & blue
C2
111
Error code is
shown after
three failed
attempts at
ignition
6 Disconnected/damaged hi-limit switch. (Refer to section 10-11)
Visual inspection: connection/breakage of wires.
Normal: 1 Ω or less between blue & blue
C1
