Chamberlain LiftMaster Security+ 3800E, Owner'S Manual

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Your garage door opener is programmed with self-diagnostic
capabilities. The “Learn” button/diagnostic LED will flash a
number of times then pause signifying it has found a potential
issue. Consult Diagnostic Chart below.
Diagnostic Chart
Symptom: One or both of the Indicator lights on the safety reversing sensors
do not glow steady.
• Inspect sensor wires for a short (staple in wire), correct wiring polarity (black/white
wires reversed), broken or disconnected wires, replace/attach as needed.
• Disconnect all wires from back of motor unit.
• Remove sensors from brackets and shorten sensor wires to 1-2 ft (30-60 cm) from
back each of sensor.
• Reattach sending eye to motor unit using shortened wires. If sending eye indicator
light glows steadily, attach the receiving eye.
• Align sensors, if the indicator lights glow replace the wires for the sensors. If the
sensor indicator lights do not light, replace the safety reversing sensors.
Symptom: LED is not lit on door control.
• Inspect door control/wires for a short (staple in wire), replace as needed.
• Disconnect wires at door control, touch wires together. If motor unit activates,
replace door control.
• If motor unit does not activate, disconnect door control wires from motor unit.
Momentarily short across red and white terminals with jumper wire. If motor unit
activates, replace door control wires.
Symptom: Sending indicator light glows steadily, receiving indicator light is
dim or flashing.
• Realign receiving eye sensor, clean lens and secure brackets.
• Verify door track is firmly secured to wall and does not move.
Symptom: Motor has overheated; the motor unit does not operate = Motor unit
hums briefly; RPM Sensor = Short travel 6-8" (15-20 cm).
• Unplug unit to reset. Try to operate motor unit, check diagnostic code.
• If it is still flashing 5 times and motor unit moves 6-8" (15-20 cm), replace
RPM sensor.
• If motor unit doesn’t operate, motor unit is overheated. Wait 30 minutes and retry. If
motor unit still will not operate replace logic board.
Symptom: Door reverses while closing.
• Check for possible door obstructions and remove.
• Check that the cable tension monitor is properly connected to the operator.
• Replace the cable tension monitor.
Cable tension monitor
reversal.
Motor overheated or
possible RPM sensor
failure. Unplug to reset.
Safety reversing sensors
slightly misaligned
(dim or flashing LED).
Door control or
wire shorted.
Safety reversing sensors
wire shorted or black/
white wire reversed.
Safety reversing sensors
wire open (broken or
disconnected).
1 FLASH
2 FLASHES
3 FLASHES
4 FLASHES
5 FLASHES
9 FLASHES
OR
“Learn”
Button LED
or Diagnostic
LED
“Learn”
Button
Motor
Unit
Installed
Safety Reversing
Sensor