Section 568 (Air Bag Restraint Systems (Service Information)): CLOCKSPRING: Operation

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

The clockspring is a mechanical electrical circuit component that is used to provide continuous electrical continuity between the fixed instrument panel wire harness and certain electrical components mounted on or in the rotating steering wheel. On this model the rotating electrical components include the driver airbag, the horn switch, the speed control switches, and the remote radio switches, if the vehicle is so equipped. The Steering Control Module (SCM)/clockspring case is positioned and secured near the top of the steering column. The fixed connector receptacles on the back of the fixed SCM/clockspring case connect the clockspring to the vehicle electrical system through two take outs with connectors from the instrument panel wire harness.

The clockspring rotor is movable and is keyed so as to move with the rotation of the steering column shaft and the steering wheel. The lower surface of the clockspring rotor hub engages and indexes the clockspring rotor to the turn signal cancel cam. Two short, yellow-sleeved pigtail wires on the upper surface of the clockspring rotor connect the clockspring to the driver airbag, while a steering wheel wire harness and a driver airbag jumper harness connected to the two connector receptacles on the upper surface of the clockspring rotor complete circuits to the horn switch, the two speed control switches and, if the vehicle is so equipped, to the optional remote radio switches on 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 SCM/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 other steering components. The clockspring must be re-centered following completion of this service or the tape may be damaged.

Service replacement SCM/clocksprings are shipped pre-centered and with a locking pin installed. This locking pin should not be removed until the SCM/clockspring has been installed on the steering column. If the locking pin is removed before the SCM/clockspring is installed on a steering column, the clockspring centering procedure must be performed. (Refer to ELECTRICAL/RESTRAINTS/CLOCKSPRING - STANDARD PROCEDURE - CLOCKSPRING CENTERING) .