Wipers stop mid-screen: park switch and linkage

A wiper motor turns continuously in one direction; a linkage converts that rotation into the sweep. When you switch off, the motor must keep running until the blades reach the bottom, then stop.

A park switch inside the motor assembly tells it when that position is reached. When wipers stop wherever they happen to be, that mechanism is the suspect.

Related: windscreen wiper system faults.

What the park switch does

A set of contacts inside the motor, driven by the gear. Their state tells the circuit whether the motor is at the park position.

Switch the wipers off mid-sweep and the park circuit keeps the motor powered — through a separate path — until park is reached, then breaks the supply.

Failure of that switch means the motor stops the instant you switch off, wherever the blades are.

Causes

Worn or corroded park switch contacts

The most common. The contacts operate every time the wipers are used, for years, and eventually pit or corrode.

Sometimes serviceable by opening the motor gearbox cover and cleaning the contacts and the track. On many motors that is a genuine repair rather than a bodge.

Water in the motor

The motor sits in the scuttle area under the windscreen, which is designed to drain. A blocked scuttle drain fills that area with water, and the motor sits in it.

If the wiper motor area is damp, fix the drain first — otherwise the replacement fails the same way.

Blocked scuttle drains cause several other problems too: damp carpet and electrical faults and water leak into cabin.

Worn linkage

The linkage uses ball joints that wear. Symptoms: blades that do not sweep as far as they used to, that judder, or that land in a different place each time.

A worn linkage can also let a blade hit the pillar or the bonnet, which damages both.

The stalk switch

Less common, but the park function runs through the switch on some vehicles.

Wrong blades or incorrect fitting

Worth checking before anything internal. Blades that are too long can foul the pillar and stop early. Blades fitted at the wrong angle land wrong.

The other version: wipers that will not stop

The opposite failure, from the same mechanism.

If the park switch fails in the state that says “not at park”, the motor never receives the signal to stop — and the wipers run continuously until you remove the fuse.

That is a park switch fault too, and it is more urgent because it flattens the battery and wears the blades.

Snow and ice: the avoidable damage

Wipers frozen to the glass, or trying to move a heavy load of snow, strain the motor and the linkage.

Do not use the wipers to clear snow, and do not force frozen blades. Lift them or de-ice the glass first.

Many systems have a thermal cut-out that stops the motor when it overheats — which then appears as wipers that stop working and mysteriously recover.

De-icing and frozen locks and winter car preparation checklist.

Rear wipers

Same principles, separate motor, and rear wiper motors live in an even wetter environment inside the tailgate.

Water entering there also affects the wiring loom that passes through the tailgate hinge, which is a common failure point for several rear functions at once.

Rear wiper and tailgate electrics and boot or tailgate will not open.

Step by step

1. Check the blades are the correct length and correctly fitted.
2. Check the scuttle area for standing water and blocked drains.
3. Watch where they stop — mid-sweep every time points at the park switch.
4. Check the fuse and relay if they do not move at all.
5. Inspect the linkage for play at the joints.
6. Consider cleaning the park contacts before replacing the motor.

Try it on the free tier of the app — pair an ELM327 adapter for the engine side of diagnostics. Wiper park faults are mechanical, and the drains under the windscreen are where to start.