Why Your Automatic Gate Opens Then Stops or Reverses

A gate that stops partway, or starts closing and then reverses, is one of the most common repair calls. It is often the system doing its job. Automatic gates are designed to stop when something seems wrong, and the trick is working out what the gate thinks is wrong.

How the gate decides to stop

Most modern gate controllers watch two things while the gate moves.

The first is the load on the motor. The control board measures how hard the motor is working, often through current draw or speed. If the load climbs above a set level, the board treats it as an obstruction and stops or reverses. This is what stops a gate crushing a car, a pet or a person.

The second is input from safety devices, mainly the photo-electric beams across the opening. If something breaks the beam while the gate is closing, the board stops and usually reopens.

That means a gate stopping or reversing is either sensing extra resistance or receiving a signal from a safety device. Almost every cause on this list fits one of those two.

Cause 1: Something in the safety beams

If your gate opens normally but stops or reverses when closing, the safety beams are the first place to look. Beams generally only act during closing.

Common culprits:

• Spider webs across the lens, especially in autumn
• Leaves, grass or a plant that has grown into the beam path
• A bin, pot or car parked across the line
• A beam post knocked out of alignment
• Low sun shining straight into the receiver, which can confuse some beams at certain times of day

Check both beam units and wipe the lenses with a soft cloth. Many beams have a small indicator light that changes when they are aligned. If cleaning does not help, the beam may be faulty or the cable damaged. Do not bridge out the beams to get the gate working. That removes a safety function. Have them repaired instead. Our safety sensors and servicing page explains what a technician checks.

Cause 2: The gate is harder to move than it used to be

If the gate stops at the same place every time, or slows before stopping, the motor is likely meeting extra resistance. On a sliding gate that could be:

• Debris in the track, such as leaves, gravel or sand
• A worn or seized roller
• A bent track section
• Worn top guides letting the gate lean and rub
• A rack that has dropped and is meshing badly with the drive gear

On a swing gate it could be:

• Worn hinges letting the leaf sag and drag
• A post that has moved
• A worn arm pivot or loose bracket
• Wind pushing against a solid leaf

The simplest test is to use the manual release, then move the gate by hand through its full travel. If it binds, scrapes or is much heavier in one spot, that is your problem. Read our guide to using the manual release safely first, especially on a sloping driveway. Then see sliding gate track and roller repairs or swing gate hinge and arm repairs.

Cause 3: A tired battery

Many residential gates run from a battery charged by mains or solar. As the battery ages, it may deliver enough power to start the gate but not enough to finish, especially on a heavy gate or after several cycles in a row. The board sees the motor slow down, reads it as an obstruction and stops.

Clues that the battery is to blame:

• The gate works first thing in the morning but fails later in the day
• It gets worse in hot weather or after several cloudy days on solar
• The control board beeps or shows a low battery warning

Battery testing is part of any service. Replacing a battery is usually far cheaper than replacing a motor.

Cause 4: Limits have drifted

The board needs to know where open and closed are. On some motors, this is learned electronically; on others, it uses physical limit switches or magnets. If the limits drift, the gate may stop short or push against its stop and reverse, thinking it has hit an obstruction. Resetting limits is usually a quick job for a technician.

Cause 5: The motor is overheating

Gate motors have a duty rating, which is how much they can work before needing to cool down. A busy shared driveway, a heavy gate or a hot day can push a motor to its limit, and thermal protection may cut in. If the gate stops after several cycles close together and then works again later, overheating is a possibility. It can also indicate the motor is undersized for the gate. See gate motor replacement if that is the case.

What you can safely check yourself

• Clear the track and around the gate
• Clean and check the safety beams
• Look for anything new in the gate's path
• Note whether the problem happens at the same point, the same time of day, or in certain weather
• Write down any beep pattern or indicator lights

Do not open the control box on a mains-powered system, and do not adjust board settings unless you know what you are doing. Electrical wiring work in NSW must be done by a licensed electrician.

When to call a technician

If the simple checks do not fix it, or the gate is noisy, grinding or behaving erratically, it is time for a technician. Send us an enquiry through the contact page with what you have noticed. We pass it on to an independent local technician who can diagnose the fault and quote the repair. More detail is on our automatic gate repairs page.