Upper Probe Short; Flame Probe Short - A.O. Smith BTX-100 Service Handbook

ULTRA HIGH EFFICIENCY POWER VENT/POWER DIRECT VENT - SERVICE MANUAL
FAULT MESSAGES (CONT)
DISPLAYED MESSAGE
CONDITION/INDICATES

"Upper Probe Short"

The control system has detected less than 390
ohms from the Temperature Probe on top of the
water heater.

"Flame Probe Short"

The control system has detected that the flame
sensor is grounded.
Technical Literature Department
Servicing should only be performed by a Qualified Service Agent
• Check all wiring between the Temperature
Probe and the J7 Socket on the CCB (page 36).
Repair/replace anything worn or damaged.
• Unplug J7 plug from CCB, check resistance
between the two black wires in the plug end with
an ohm meter. If resistance is at or below 390
ohms - replace the Temperature Probe.
• Call the technical support phone number shown
on the water heater labeling for further assis-
tance if the problem has not been corrected
after performing the procedures outlined here.
• Disconnect the wire from the flame sensor (see
pages 12 and 24). Check for continuity between
flame sensor and ground with an ohm meter.
There should be no continuity - infinite resis-
tance.
• If above test indicates there is continuity
between the flame sensor and ground - remove
the flame sensor (see pages 12 and 24). Ensure
the flame sensor is not bent and touching the
burner.
• Check all flame sensor wiring between the
flame sensor and the J4 male spade connector
on the CCB (page 36). Ensure there are not any
pinched wires or shorts - repair/replace anything
worn or damaged.
• Replace the flame sensor.
• Call the technical support phone number shown
on the water heater labeling for further assis-
tance if the problem has not been corrected
after performing the procedures outlined here.
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CHECK/REPAIR
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