Question 1

i get a single flash from the led light on the motor unit when i try to operate it, then nothing

Accepted Answer

DIAGNOSIS A single flash indicates a problem with the safety reversing sensors. Their alignment is off or the wiring is damaged. FIX Check the sensor alignment. The LED on each sensor (one has a green light, the other amber) must be solid, not blinking. Loosen the bracket and aim the sensors directly at each other until both lights are steady. Tighten the bracket. IF THAT DIDN'T WORK Check the wire connections at the back of the motor unit. A loose or corroded pin in the sensor terminal block (usually labeled 1 and 2) will cause this. Unplug the opener and reseat the wires. HEADS UP Sunlight directly hitting the sensor lens can overwhelm the receiver. Shield the lenses with the included sun shades or a small piece of tubing if this happens in the afternoon.

Question 2

my opener's light won't turn off automatically anymore, it just stays on for hours

Accepted Answer

DIAGNOSIS The auto-light timer feature is disabled or malfunctioning. The light duration is controlled by a setting on the logic board. FIX Reset the light timer. Press and hold the light button on the wall console for 10 seconds. You should hear a beep from the motor unit. This resets it to the default (approx. 4.5 minutes). IF THAT DIDN'T WORK The logic board's light relay may be stuck 'on'. Unplug the opener for 30 minutes to let the board fully power down and reset. If it's still stuck on after plugging back in, the board needs replacement. HEADS UP A light that stays on constantly will burn out the bulb prematurely and can generate enough heat to be a concern inside the motor housing.

Question 3

the travel limits keep drifting on my opener, i set them and a week later the door doesn't close all the way

Accepted Answer

DIAGNOSIS The limit adjustment knobs on the back of the motor unit are loose or the control board is faulty. The 8355W uses manual dials, not electronic settings. FIX First, reset the limits firmly. Unplug the opener. Turn both the 'UP' and 'DOWN' limit dials fully counter-clockwise. Plug it in. Run the door down manually to the fully closed position. Now, adjust the 'DOWN' dial clockwise until the door light blinks. That's the set point. IF THAT DIDN'T WORK The potentiometers inside the dials are worn. The entire logic board may need replacement (part #41A5021). Drifting limits is a known symptom of a failing board. HEADS UP When limits drift, the door can try to travel too far. This puts extreme stress on the trolley, belt, and door. Fix it promptly to avoid a bigger repair.

Question 4

how do i clear all my old remotes from my liftmaster 8355w, i lost a few and want to start fresh

Accepted Answer

DIAGNOSIS You need to perform a factory reset of the opener's memory. This erases all remote controls and keyless entry codes. FIX Press and hold the learn button (yellow, under the light lens) for about 10 seconds. Release when the LED light next to it turns off. All previous codes are now cleared. The light will come back on solid. IF THAT DIDN'T WORK Some models require a slightly different sequence. Try holding the learn button for 6 seconds until the light blinks, then release and immediately press and hold it again for another 10 seconds until the light goes off. HEADS UP This will also erase your wall console and keypad. You must re-program every device after the reset, including the wall console inside your garage.

Question 5

my garage door only opens about a foot then stops and goes back down, sensors are clear

Accepted Answer

DIAGNOSIS The force limits are set too low. The opener thinks it's hitting an obstacle. On the 8355W, there are separate 'Up' and 'Down' force adjustments. FIX Adjust the 'Up' force. On the back of the motor unit, find the two black adjustment dials next to the learn button. Turn the 'UP' force dial (usually the left one) clockwise one notch. Test. Repeat if needed, but only small increments. IF THAT DIDN'T WORK The door springs are out of balance. Manually disconnect the opener using the red emergency release cord. Lift the door halfway. If it doesn't stay put, the springs are weak. A professional must adjust or replace them. HEADS UP Do not over-adjust force settings. The door should reverse on a 2x4 placed on the floor. If it doesn't, the force is too high and unsafe.

Question 6

the yellow learn button light on my liftmaster is just solid, won't blink when i press it, can't add remotes

Accepted Answer

DIAGNOSIS The opener is in 'lock mode'. This prevents any new remotes or consoles from being programmed. It's a security feature. FIX Take the opener out of lock mode. Press and hold the square 'lock' button on your wall console for 2 seconds until the light changes. The learn button LED on the motor unit should now blink when pressed. IF THAT DIDN'T WORK The logic board may have a fault. Unplug the opener from power for 60 seconds. Plug it back in. This resets the board. The learn light should now be off. Press it to see if it blinks. HEADS UP Lock mode does not affect already programmed devices. They will still work. This only blocks new programming attempts.

Question 7

my garage door opener makes a horrible grinding noise only when going down, sounds like metal on metal

Accepted Answer

DIAGNOSIS The trolley carriage or the opener's drive gear is worn out. On a belt drive like the 8355W, this is usually the nylon drive gear inside the motor head. FIX You need a replacement gear kit (part #41A2036). Unplug the opener. Remove the cover. You'll see the gear assembly on the motor shaft. Follow a video guide to swap it. The job takes about an hour. IF THAT DIDN'T WORK The noise is from the door itself, not the opener. Check the door's metal rollers and hinges. A dry, seized roller will grind. Lubricate all moving parts on the door track with white lithium grease. HEADS UP Do not run the opener with a stripped drive gear. You will burn out the motor. If the motor runs but the door doesn't move, the gear is definitely stripped.

Question 8

my liftmaster 8355w opener just beeps at me when i try to use the wall button, the remote works fine though

Accepted Answer

DIAGNOSIS The wall console is not communicating with the motor unit. This is a weak or lost wireless signal between them. FIX Re-sync the wall console. Press and hold the learn button on the motor unit (yellow, under the light lens) until the LED blinks. Within 30 seconds, press and hold the 'door' button on the wall console until the motor unit light blinks twice. Test it. IF THAT DIDN'T WORK The wall console battery is dead. It uses a CR2032. Pop the cover off and replace it. Re-sync after. HEADS UP The wall console must be within 10 feet of the motor unit with a clear line of sight for the initial sync. Metal siding or foil insulation can block the signal.

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