Chamberlain 3800PC 1 FLASH, FLASHES, FLASHES, FLASHES, FLASHES, FLASHES, Diagnostic Chart, wire shorted, disconnected), Cable tension, wire shorted or, Door control or

Motor

Unit

“Learn” Button LED or Diagnostic

LED

“Learn” Button

Installed

Safety Reversing

Sensor

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

1 FLASH		Symptom: One or both of the Indicator lights on the safety reversing sensors
Safety reversing sensors		do not glow steady.
		• Inspect sensor wires for a short (staple in wire), correct wiring polarity (black/white
wire open (broken or
		wires reversed), broken or disconnected wires, replace/attach as needed.
disconnected).		• Disconnect all wires from back of motor unit.
	OR
		• Remove sensors from brackets and shorten sensor wires to 1-2 ft (30-60 cm) from
		back each of sensor.
2	FLASHES
		• Reattach sending eye to motor unit using shortened wires. If sending eye indicator
Safety reversing sensors		light glows steadily, attach the receiving eye.
		• Align sensors, if the indicator lights glow replace the wires for the sensors. If the
wire shorted or
black/white wire reversed.		sensor indicator lights do not light, replace the safety reversing sensors.

3	FLASHES	Symptom: LED is not lit on door control.
Door control or		• Inspect door control/wires for a short (staple in wire), replace as needed.
Door control or		• Disconnect wires at door control, touch wires together. If motor unit activates,
wire shorted.
wire shorted.		replace door control.
		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.

4	FLASHES	Symptom: Sending indicator light glows steadily, receiving indicator light is
		dim or flashing.
Safety reversing sensors
		• Realign receiving eye sensor, clean lens and secure brackets.
slightly misaligned
		• Verify door track is firmly secured to wall and does not move.
(dim or flashing LED).

5	FLASHES	Symptom: Motor has overheated; the motor unit does not operate = Motor unit
		hums briefly; RPM Sensor = Short travel 6-8" (15-20 cm).
Motor overheated or
		• Unplug unit to reset. Try to operate motor unit, check diagnostic code.
possible RPM sensor
		• If it is still flashing 5 times and motor unit moves 6-8" (15-20 cm), replace RPM
failure. Unplug to reset.
		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.

9	FLASHES	Symptom: Door reverses while closing.
Cable tension		• Check for possible door obstructions and remove.
Cable tension		• Check that the cable tension monitor is properly connected to the operator.
monitor reversal.

• Replace the cable tension monitor.