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To prevent possible SERIOUS INJURY or DEATH from a closing garage
• Activate door ONLY when it can be seen clearly, is properly adjusted,
and there are no obstructions to door travel.
• ALWAYS keep garage door in sight until completely closed. NEVER
permit anyone to cross path of closing garage door.
PRE-INSTALLATION SYSTEM TEST
1. The sensor and receiver are pre-matched (programmed) at the
factory. Test the system by flipping the sensor over while it is a
few feet away from the receiver. The receiver will show a
green light for closed when the sensor is face up in the vertical
position with the round end of the case pointing down
(Figure 1). The red light will flash when the sensor is face
down in the horizontal position (Figure 2).
2. If the green or the red receiver lights do not come on, or do
not react as described, see the Troubleshooting or Learning
section of these instructions.
INSTALLING THE BATTERY IN THE GARAGE
DOOR INDICATOR SENSOR
1. Place the screw driver blade on the tab at
the end of the case and gently press down
and in toward the case.
2. Insert the the lithium battery into the battery
clip with the + (positive) side face up.
3. Push the case back together tightly by
inserting the top hooks into the back cover,
then snap shut the bottom of the case.
NOTE: It is normal to hear a rattle from the tilt
switch in the sensor when tilted or rotated to
INDOOR RECEIVER SETUP
1. Plug the AC adapter into any
standard 110 volt AC electrical
wall outlet and the small plug
into the back of the indoor
2. The receiver has a 9" antenna
wire which comes out the back.
The antenna should be straight
and not touching metal.
Figure 1 Figure 2
NOTE: Because radio control devices are inherently susceptible
to RF interference, this product should NOT be used as a
stand-alone security device. This product is considered a
monitoring and notification device ONLY, and as such, should not
be used as a substitute for a dedicated home security system.
To ensure that your Garage Door Monitor continues to operate
properly, the following checks should be performed on a
• Check that the sensor is mounted properly on the garage door
(see Mounting the Sensor section of this manual.)
• Ensure the 3 volt lithium battery is installed properly.
• Check to see that the receiver system is plugged into a wall
outlet and the jack is properly connected to the back of the
receiver. Make sure the antenna is straight and not in contact
with any metal objects.
• Check that the receiver is properly recognizing sensor
signals (see Troubleshooting section of this manual.)
MOUNTING THE SENSOR
Attach the sensor to the inside of the garage door using the
double-sided fastening strip. Mount the sensor near the top of the
garage door for best results. The round end of the case should
be pointing down when the garage door is closed.
Inside of Garage
Double-Sided Fastening Strip
Know when your garage door is open
Thank you for purchasing the LiftMaster Garage Door Monitor.
Monitor the status of your garage door from inside your home. No
longer will you have to run downstairs or go outside just to see if
you or your children have left the garage door open.
Garage Door Monitor
Models 915LM • 916LM • 2C507-2