Chamberlain JDC - Page 61

61
Troubleshooting (continued)
Code
Display
Message
Description
Possible
Causes
Diagnosis Resolution
F102 F102 BBU
DISCONN
Battery is
learned to the
system but
the battery is
not detected
Backup battery
is disconnected
Verify all battery wiring is
connected securely and
properly to the correct
terminals and with the
correct polarity.
Correct any wiring issues.
Battery is worn
out or has failed
Batteries can be tested
with a suitable battery
tester.
Older batteries are more
likely to be worn out, as
are batteries that are
used often.
Replace batteries.
Always replace both batteries
as a set. Do not mix old and new
batteries or use mismatched
types.
Battery fuses
blown
Visually inspect battery
fuses or measure the
fuses with a multimeter
for continuity.
If fuses are blown, replace both
together with new fuses.
F105 F105 AC
FAIL
AC failure.
System is
running on
battery.
Power outage Check for proper voltage
at the input of the
operator
Error code will resolve when
power is restored
Input voltage
outside
specications
Check for proper voltage
at the input of the
operator
Ensure voltage supplied to the
operator is within the specied
operating range
F106 F106 WC
SHORT
Indicates wall
control is
removed and
jumpered out.
Wall control is
intentionally
disconnected
Error message is
informational only.
Liftmaster strongly recommends
using the provided LCD wall
control with the operator.
Wiring short
circuit
Inspect wiring for short
circuits, damage, etc.
Resolve any faults found, then
power cycle the operator
Damaged wall
control
Replace wall control with
known-good unit, then
power cycle the operator
If known good wall control
resolves the issue, replace the
bad wall control
F120 F120 MAINT
DUE
Maintenance
counter
reached
preset limit
Maintenance
counter
reached preset
limit
F120 error code Reset maintenance counter
using the menu through the wall
control
F121 F121 OVER
CYCLED
Standard/
extended
cycle count
reached
Operator has
been cycled too
many times in a
short period of
time
Refer to specied cycle
ratings for the operator
model that is installed
Reduce cycle rate to ensure it
is within specications for the
operator