The most common causes
Safety photocells are the first place many people look, but the complete closing circuit matters. A blocked, misaligned, flat-battery or water-affected beam can hold the controller open. Vehicle loops, safety edges, timers, key switches and access systems can do the same
Limit switches, encoder position, control-board logic and the physical gate can also prevent closing. A heavy section of travel may be interpreted as an obstruction
- Blocked or misaligned photocells
- Damaged wiring or low wireless-beam batteries
- Vehicle loop held active
- Close limit or encoder fault
- Heavy gate movement or damaged track
- Hold-open timer or access command
Safe checks before calling
Remove obvious objects from the gate path and clean the photocell lenses with a soft cloth. Check whether an emergency stop, hold-open switch or isolation device has been operated
Do not put hands near hinges, rollers, chains or racks, and do not bypass a safety terminal unless you are qualified and controlling the risk
What a technician should test
A proper diagnosis confirms which controller input is preventing closure, then determines why that input is active. The test should include the gate’s physical movement, limits, motor response and every safety device involved in closing
Intermittent faults should be investigated for water ingress, loose connections, failing batteries, damaged cable and movement of posts or brackets
Automatic gates and doors can cause serious injury. Keep clear of moving equipment and live electrical parts. If operation is unpredictable or unsafe, isolate the system where practical and arrange professional assessment