Clockspring Assembly / Spiral Cable: Description and Operation

Clockspring:

The clockspring assembly is secured with two screws onto the multi-function switch housing near the top of the steering column directly below the steering wheel. The clockspring consists of a flat, round molded plastic case that contains a spool-like molded plastic rotor with a large exposed hub covering the entire upper surface of the case. The rotor hub has a large center hole that is internally ribbed to engage splines on the upper steering column shaft, and two small clearance holes that provide access to the case mounting screws. The lower side of the rotor hub also serves as an integral molded plastic turn signal cancel cam.

A single connector receptacle on the upper surface of the rotor has pigtail wires that connect to the horn switch and the driver airbag on the steering wheel, while a single connector receptacle on the lower surface of the case has pigtail wires that connect the clockspring to the vehicle wire harness on the steering column. Within the plastic case and wound around the rotor spool is a long ribbon-like tape that consists of several thin copper wire leads sandwiched between two thin plastic membranes. The outer end of the tape terminates at the connector receptacle that faces the steering column, while the inner end of the tape terminates at the connector receptacle on the hub of the clockspring rotor that faces the steering wheel.

Service replacement clocksprings are shipped pre-centered and with the mounting screws backed out from the case far enough to engage the access holes in the upper surface of the rotor. The mounting screws secure the centered clockspring rotor to the clockspring case during shipment, but allow free rotation of the rotor once the clockspring is properly installed on the steering column.

The clockspring cannot be repaired. If the clock-spring is faulty, damaged, or if the driver airbag has been deployed, the clockspring must be replaced.

The clockspring is a mechanical electrical circuit component that is used to provide continuous electrical continuity between the fixed vehicle wire harness and the electrical components mounted on or in the rotating steering wheel. On this model the rotating electrical components include the driver airbag and the horn switch. The clockspring case is positioned and secured to the multi-function switch housing near the top of the steering column. The connector receptacle on the underside of the fixed clockspring case connects the clockspring to the vehicle electrical system through two take outs with connectors from the vehicle wire harness.

The clockspring rotor is movable and is keyed by integral molded ribs on the inner circumference of the rotor hub to the splines on the external circumference of the upper steering column shaft. The two integral lobes of the turn signal cancel cam formation on the lower surface of the clockspring rotor hub contact the turn signal cancel actuator of the multi-function switch to provide automatic turn signal cancellation. The yellow sleeved pigtail wire on the upper surface of the clockspring rotor connects the clockspring to the driver airbag, while two single pigtail wires connect to the feed and ground terminals of the horn switch located within the hub cavity of the steering wheel.

Like the clockspring in a timepiece, the clockspring tape has travel limits and can be damaged by being wound too tightly during full stop-to-stop steering wheel rotation. To prevent this from occurring, the clockspring is centered when it is installed on the steering column. Centering the clockspring indexes the clockspring tape to the movable steering components so that the tape can operate within its designed travel limits. However, if the clockspring is removed from the steering column or if the steering shaft is disconnected from the steering gear, the clockspring spool can change position relative to the movable steering components. The clockspring must be re-centered following completion of this service or the tape may be damaged.

Service replacement clocksprings are shipped pre-centered and with the mounting screws backed out from the case far enough to engage the access holes in the upper surface of the rotor. The mounting screws secure the centered clockspring rotor to the clockspring case during shipment, but allow free rotation of the rotor once the clockspring is properly installed on the steering column. The clockspring mounting screws should not be tightened into the clockspring case until the clockspring has been installed on the steering column. If the screws are tightened into or removed from the case before the clockspring is installed on a steering column, the clockspring centering procedure must be performed.