Description And Operation: CLOCKSPRING

The clockspring is located near the top of the steering column, directly beneath the steering wheel. It allows circuit continuity for the DAB and all other circuits used in the steering wheel. The clockspring for this vehicle is secured to and integral to the SCCM near the top of the steering column below the steering wheel. The clockspring includes an integral, internal turn signal cancel cam that is serviced as a unit with the SCCM. The SCCM also includes the left (lighting) multifunction switch and the right (wiper) multifunction switch. Each of these switches and the wiring between the switches and the clockspring should not be separated and are serviced only as a complete assembly with the SCCM. The SCCM case includes integral tabs on the back for mounting the unit with a band clamp to the steering column support tube.

The SCCM case includes a connector receptacle near the top of the back of the unit facing toward the instrument panel which contains the circuits for the multifunction switches. The connectors near the bottom of the unit contain the circuits for the clockspring and the receptacles on the steering wheel side of the clockspring. The connector receptacles on the steering wheel side of the clockspring contain the circuits for the other switches mounted on the steering wheel. Within the plastic clockspring case is a spool-like molded plastic rotor with a large exposed hub. The upper surface of the rotor hub has a large center hole and short pigtail wires with connectors. The pigtail connectors contain the circuits for the Driver AirBag (DAB).

The service replacement SCCM is shipped pre-centered and has a spring actuated molded plastic automatic locking ring installed. The automatic locking ring secures the centered clockspring rotor to the SCCM case during shipment and handling, and automatically releases the rotor when the steering wheel is installed. However, it is recommended that an additional strap be installed through the two retainer loops integral to the outer circumference of the SCCM to secure the rotor to the case whenever the SCCM is removed from the steering column to prevent accidental loss of clockspring centering.

The clockspring is a mechanical electrical circuit component that is part of the SCCM and is used to provide continuous electrical continuity between the instrument panel wire harness and certain electrical components mounted on or in the steering wheel. On this vehicle the electrical components include the DAB, the Electronic Vehicle Information Center (EVIC) switches, the horn switch, the remote radio switches, the speed control switches and the hands-free communication switches, if the vehicle is so equipped. The clockspring is positioned and secured to the SCCM near the top of the steering column. The connector receptacles on the back of the SCCM connect the electrical components that connect to the steering wheel side of the SCCM to the vehicle electrical system through take outs and connectors from the instrument panel wire harness.

The turn signal cancel cam is integral to the rim of the SCCM rotor hub within the SCCM, so it also moves with the rotation of the steering wheel. Short pigtail wires on the upper surface of the SCCM connect the SCCM to the DAB. A wire harness connects to the EVIC switches, the horn switch, the speed control switch and, if the vehicle is so equipped, the optional remote radio and hands-free communication switches on the steering wheel.

Like the clockspring in a timepiece, the SCCM 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 SCCM is centered when it is installed on the steering column. Centering the SCCM indexes the SCCM tape to the movable steering components so that the tape can operate within its designed travel limits. If the steering wheel is removed from the steering column or if the SCCM is removed from the steering column, a spring-actuated automatic locking ring pops up from the face of the SCCM rotor to lock the rotor from rotation. However, if the locking ring is manually compressed or if the steering shaft is disconnected from the steering gear with the steering wheel installed, the SCCM spool can change position relative to the other steering components. Loss of SCCM centering will result in damage to the SCCM tape.

Service replacement SCCMs are shipped pre-centered and with a plastic locking pin installed. This locking pin should not be removed until the SCCM has been installed on the steering column. If the locking pin is removed before the SCCM is installed on a steering column, SCCM centering may be compromised.

The hard wired SCCM circuits may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SCCM squib circuits for the SRS. The most reliable, efficient and accurate means to diagnose the circuits related to SRS operation requires the use of a diagnostic scan tool and may also require the use of the Airbag Kit. Refer to the appropriate diagnostic information.

The clockspring cannot be repaired. If the clockspring is ineffective, damaged, or if the DAB has been deployed, the entire SCCM must be replaced. Refer to MODULE, STEERING COLUMN CONTROL (SCCM), REMOVAL AND INSTALLATION .