Glossary term
controller
The electronic brain that reads calls and safety signals, drives the motor and doors, and records faults.
What it means
The controller decides what the lift does. It collects landing and car calls, checks that every safety contact is closed, tells the drive where to go, and manages the doors at each stop. It also keeps a fault log, which is often the fastest route to a diagnosis.
Where you see it
In the machine room, in a cupboard beside the shaft, or in the top of the door frame on machine-room-less lifts. On stairlifts and platform lifts it is a small board inside the carriage or mast.
How it works
The controller will not start a journey until the safety chain is complete. When it refuses, it usually records why, as a fault code or a lamp pattern.
Modern controllers also learn normal behaviour — door travel, floor positions, motor current — and flag deviations. That is why a mechanical problem often shows up first as a controller fault.
Why it matters
Reading the fault log turns guesswork into a targeted repair. Owners help most by recording the code, the floor and the time.
Commonly confused with
The controller is often called the motherboard or the computer, and people expect it to be the fault whenever a lift stops. In practice the controller is usually working correctly and is deliberately stopping the lift because a safety input told it to. It is the messenger far more often than it is the cause.
Wear, service and lifespan
Controllers last decades but their relays, contactors and backup batteries do not. Service work reads the fault log, clears stored events, checks the contactors for pitting and confirms the date and time so future logs make sense. Older controllers eventually reach a point where spares are no longer made, which is when a modernisation is discussed.
Signs to watch for
- The lift is powered but ignores calls.
- A fault code or flashing light on the panel or display.
- Behaviour changed after a power cut.
- The lift parks at one floor with doors open.
- Intermittent faults that clear themselves.
Troubleshooting controller
The display shows a code and the lift will not accept calls
What it usually means: The controller has latched a fault and needs an engineer to inspect and reset it
Safe check: Photograph or write down the exact code and the time it appeared.
Calls register but the car takes a long time to answer
What it usually means: Traffic settings, a door delay, or the lift is answering another call first
Safe check: Time the wait at a quiet hour and compare it with a busy one.
The same fault returns days after every reset
What it usually means: A repeating input fault, not a one-off glitch
Safe check: Keep a simple dated list of each occurrence and hand it over at the next visit.
How to report it
Quote the code exactly as shown, including letters and leading zeros, and say what the lift was doing when it appeared. Add whether power was interrupted recently. A photograph of the display is worth more than any description, and it lets the engineer look the code up before arriving.
Ask us about controller on your lift
Tick anything you can see or hear from where you normally stand, add a note in your own words, and we will put it into the message below for you. Never open, force or enter any part of the lift to check.
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Send the make, model, error code and what the lift does now. We reply by email and point you to the right help.
Related terms
Definitions that usually come up alongside controller when you are describing a fault.
- fault code
A number, letter sequence or lamp pattern the controller shows to identify why it stopped.
Controls and electrics
- interlock
A lock and switch combined, so a door cannot be opened unless the car is there and the lift cannot move unless the door is locked.
Safety devices
- door operator
The motor and gear on top of the car that opens and closes the doors and reports their position to the controller.
Doors and entrances
- emergency stop
A latching switch that cuts the drive immediately and holds the equipment stopped until it is released.
Controls and electrics
- key switch
A keyed switch that isolates or enables the equipment, used to prevent unauthorised use.
Controls and electrics