All Wound Up? Then check the clock spring!

Sometimes life can hang by the proverbial thread. Or even by a spring – a clock spring, to be precise. Integrated in the steering wheel, this coiled flat ribbon cable maintains the electrical connection to the stationary part of the vehicle. Through this connection, components such as the airbag, horn and multifunction steering-wheel buttons receive power and signals. A conventional cable would quickly fail due to the constant rotational movement of the steering wheel. The clock spring, however, winds and unwinds as the wheel turns, making it far more durable.

Wear, corrosion, extreme temperature fluctuations, vibrations or dust can, however, still impair its functionality. Moreover, steering-wheel modifications or the removal of the steering gear or steering-column switches are also frequent causes of failure. Why? Because during removal, the clock spring can unintentionally rotate, causing its center position to change. If this happens, the flat ribbon cable may become mechanically overstretched during the next steering movement and eventually tear.

The driver will not notice this immediately, but the airbag warning light will appear in the instrument panel. In such cases, the vehicle should be inspected without delay. The warning symbol typically shows a seated occupant wearing a seat belt with a circle in front representing a deployed airbag.

Other functions, such as the horn or volume controls, may also stop working. So, the next trip should therefore lead straight to a workshop. After all, who would want to keep driving without the protection of a potentially life-saving airbag?
AIC currently includes 153 clock springs in its range.