Relay Windscreen Wiper Interval. Porsche 911 1974-75  ❭  91161814900

Wiper Interval Relay 

The OE Match Wiper Interval Relay is a high-quality OEM-style replacement. This relay controls the intermittent wiping function, ensuring your windscreen wipers operate at the correct timed intervals during light rain and changing weather conditions.

Fits:

• Porsche 911 1974-1975 2.7L / 1976-77 3.0 Carrera
• Porsche 911 1975 3.0L Turbo (930)

Diagram ref no 34

Manufactured to match the original specifications, this OE Match relay provides dependable performance, direct-fit installation and reliable operation, making it the ideal replacement for ageing or failed original relays.

What Does the Wiper Interval Relay Do?

The wiper interval relay is an essential component of your Porsche's electrical system. It controls the timing circuit that activates the intermittent wipe feature, allowing the wiper blades to pause between sweeps instead of operating continuously.

By regulating the delay between each wipe cycle, the relay helps maintain clear visibility during drizzle or mist while reducing unnecessary wear on the wiper motor and blades.

The relay is responsible for:

• Controlling intermittent windscreen wiper operation.
• Delivering consistent timed wipe intervals.
• Sending electrical signals to the wiper motor.
• Providing smooth, factory-correct wiper performance.
• Improving visibility and driving safety in variable weather conditions.

Why Do Wiper Interval Relays Fail?

Electrical relays naturally deteriorate over time, particularly in classic vehicles where components may have been in service for decades. Heat, vibration and moisture can all contribute to internal wear and eventual failure.

Common causes include:

• Burnt or worn internal electrical contacts.
• Ageing electronic components.
• Corrosion caused by moisture ingress.
• Heat damage from years of continuous operation.
• Fatigued solder joints and internal circuitry.
• Oxidised terminals leading to poor electrical connections.

Original relays fitted to 1974-1975 Porsche 911 models are now approximately fifty years old, making replacement a sensible preventative maintenance upgrade.

Symptoms of a Faulty Wiper Interval Relay

A failing relay can cause several noticeable problems, including:

• Intermittent wipe function no longer operates.
• Wipers only work on continuous settings.
• Irregular or inconsistent wipe intervals.
• Delayed or erratic wiper activation.
• Wipers stopping unexpectedly during operation.
• Audible relay clicking without correct wiper movement.
• Complete loss of intermittent wipe functionality.

Replacing the relay is often the quickest and most effective way to restore normal operation.

When Should the Relay Be Replaced?

The OE Match Wiper Interval Relay should be replaced whenever intermittent wipe performance becomes unreliable or electrical testing confirms relay failure.

Many Porsche owners also choose to replace ageing relays during restoration projects or preventative maintenance to improve long-term reliability and reduce the risk of electrical faults.

A new relay helps restore dependable operation while preserving the original driving experience of your classic Porsche.

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