
LED
1-1/2" (3.8 cm) board (or a 2x4 laid flat)
Safety Reversing Sensors
ADJUSTMENT
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LiftMaster
845 Larch Avenue
Elmhurst, IL 60126-1196
STEP 1: Press and hold the black button until the LED starts flashing slowly, 
then release.
STEP 2: Push and hold the black 
button until the door reaches the 
desired UP (open) position.
STEP 3: Push the door control or 
programmed remote control. This 
sets the UP (open) limit and 
begins closing the door.
STEP 4: Immediately when the 
door begins to close, press and 
release either the black or yellow 
button. This will stop the door.
STEP 5: Push and hold the yellow 
button until the door reaches the 
desired DOWN (closed) position.
STEP 6: Once the 
door is closed, if 
there appears to 
be too much 
pressure on the 
door, you may 
toggle the door 
back and forth 
using the black 
and yellow 
buttons to reach 
the desired closed 
position.
STEP 7: Push the door control or 
programmed remote control. This 
sets the DOWN (close) limit and 
the door should open.
STEP 1: Push the yellow button twice to enter into the 
Force Adjustment Mode. The LED will flash quickly.
STEP 2: Push the door control or programmed remote 
control. The door will close (DOWN).
STEP 3: Push the door control or programmed remote 
control again. The door will open (UP).
STEP 4: Push the door control or programmed remote 
control a third time to close the door (DOWN).
Program the Travel Limits Set the Force Test the Safety Reversal System
Test the Protector System®
1. With the door fully open, place a 1-1/2 inch (3.8 cm) board 
(or a 2x4 laid flat) on the floor, centered under the garage 
door.
2. Operate the door in the down direction. The door must 
reverse on striking the obstruction. 
If the door stops on the obstruction, it is not traveling far 
enough in the down direction. Complete Adjustment Steps 1 
and 2 Program the Travel Limits and Set the Force.
Repeat the test.
1. Press the remote control push button to open the door.
2. Place the opener carton in the path of the door.
3. Press the remote control push button to close the door. The 
door will not move more than an inch, and the opener lights 
will flash.
The garage door opener will not close from a remote if the 
indicator light in either sensor is off (alerting you to the fact 
that the sensor is misaligned or obstructed).
OPTIONAL
With the door fully closed, push on 
the front of the cable tension 
monitor. A click should be heard. If 
there is no click, the roller may be 
hitting the jamb and not allowing 
the switch to detect slack in the 
cable. Make sure the cable tension 
monitor is mounted flush with the 
wall and the roller is free from any 
obstructions.
1. With the door fully closed, the power door lock bolt should 
be protruding through the track.
2. Operate the door in the open direction. The power door lock 
should retract before the door begins to move.
3. Operate the door in the down direction. When the door 
reaches the fully closed position, the power door lock 
should automatically activate to secure the door.
NOTE: If the power door lock does not function, the lock can be 
manually released by sliding the manual release handle to the 
open position.
Disengage door lock before proceeding. The door should be fully 
closed if possible. Pull down on the emergency release handle 
until a click noise is heard from the garage door opener and lift 
the door manually.
To reconnect the door to the garage door opener, pull the 
emergency release handle straight down a second time until a 
click noise is heard from the garage door opener. The door will 
reconnect on the next UP or DOWN operation.
Test the emergency release:
1. Make sure the garage door is closed. 
2. Pull the emergency release handle. The garage door should 
then be able to be opened manually. 
3. Return the door to the closed position.
4. Pull the emergency handle a second time.
5. Reconnect the door to the garage door opener.
Test Cable Tension 
Monitor
Test Power Door Lock
To Open the Door Manually
Battery Backup
Model 475LM
Secure the Battery Backup to a 
structural support (ceiling joist or 
wall stud) within 3 feet (.9 m) of 
the garage door opener. Connect 
the Battery Backup cord into the 
connector on the bottom of the 
garage door opener.
Travel limits regulate the points at which the door will stop when 
moving up or down.
The force setting measures the amount of force required 
to open and close the door.
GDOPro105
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