T-M50 / T-M50 ASME Service manual
Ver. 1.05
43
CONFIDENTIAL
Error Code
Malfunction description
Cancellation method
Fault of driving circuit for any of the gas
solenoid valves (SV
1
, SV
2
, and/or SV
3
)
(The computer checks the condition of the
solenoid valves 6 hours after every operation)
Turn off the power supply
Diagnosis
Checkpoint
551
1 Left and/or Right PCB and/or gas valve fault
(Refer to section 10-4 & 10-14)
Visual inspection of gas valves: connection/breakage of wires.
Normal: 78 to 100 VDC between COM (blue) & #9 (green)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #53 (orange)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #73 (red)
(during operation)
Visual inspection of PCB: connection/breakage of wires and/or burn marks
on the computer board.
2 Gas solenoid valve fault (SV
1
, SV
2
, and/or SV
3
)
C
Error Code
Malfunction description
Cancellation method
Fan motor fault
Turn off the power or water supply
Diagnosis
Checkpoint
611
1 PCB and fan motor fault (Refer to section 10-3,10-14 & 10-15)
Visual inspection of fan motor: connection/breakage of wires or dust
buildup (causing electrical shortage)
Normal: 110 to 160 VDC between red & blue (during operation)
Normal: 13 to 17 VDC between yellow & blue (during operation)
Normal: 2.0 to 6.5 VDC between orange & blue (during operation)
Verify fan motor speed of the water heater using the "diagnostics mode" of
the temperature remote controller. See the "12-1. How to diagnose the
water heater using the remote controller.”
Visual inspection of Left and/or Right PCB: connection/breakage of wires
and/or burn marks on the computer board.
G
