A.O. Smith T-D2-OS - Page 42

T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
42
CONFIDENTIAL
Error Code
Malfunction description Cancellation method
391
Disconnected AFR rod
Turn off
the power or water supply
Diagnosis Checkpoint
1 AFR rod fault   (Refer to section 10-6)
Visual insp
ection: connection/breakage of wires, soot on it.
I
Error Code
Malfunction description Cancellation method
441
Flow sensor failure (Only Easy
-
link system)
Turn off
the power or water supply
Diagnosis Checkpoint
1 Flow sensor failure   (Refer to section 10-9)
Visual inspection: connection/breakage of wires and/or debris on impeller.
Check voltage/resistance between (red & black) or (white & black)
H2
Error Code
Malfunction description Cancellation method
510
Fault of driving circuit for main gas solenoid
valve (MV,
SV
1
,
SV
2
and/or SV
3
)
Turn off the power supply
(The computer checks the condition of the main
gas valve immediately after every operation and
the conditions of the solenoid valves 6 hours
after every operation)
Diagnosis Checkpoint
1 PCB and/or main gas valve fault
(Refer to section 10-4 & 10-15)
Visual inspection of gas valves: connection/breakage of wires.
Normal: 78 to 100 VDC between COM (blue) & #3 (light blue)
(during operation)
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 (MV,
SV
1
,
SV
2
and/or SV
3
)
C