Clockspring - Operation

OPERATION

The clockspring is a mechanical electrical circuit component that is used to provide continuous electrical continuity between the fixed instrument panel wire harness and the electrical components mounted on or in the rotating steering wheel. On this vehicle the rotating electrical components include the driver airbag, the horn switch, the Electronic Vehicle Information Center (EVIC) switches, the speed control switches, the remote radio switches and the steering wheel heating element, if the vehicle is so equipped. The clockspring case is positioned and secured to the top of the steering column. The fixed connector receptacles on the back of the fixed clockspring case connect the clockspring to the vehicle electrical system through several take outs with connectors from the instrument panel wire harness.

The turn signal cancel cam is integral to the rim of the clockspring rotor hub within the clockspring case so it also moves with the rotation of the steering wheel. Two short, black-sleeved pigtail wires on the upper surface of the clockspring rotor connect the clockspring to the driver airbag, while a steering wheel wire harness connected to the connector receptacle on the upper surface of the clockspring rotor completes circuits to the horn switch, the speed control switch and, if the vehicle is so equipped, to the optional remote radio switches and EVIC switches on the steering wheel. A third pigtail wire is dedicated to providing the high current requirements of the heating element for the optional heated steering wheel received through a dedicated connection on the back of the clockspring through a set of slip rings internal to the clockspring case. Another connector receptacle found on the Steering Angle Sensor (SAS) on the back of the clockspring is dedicated to the inputs and outputs of the SAS.

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 and the SAS integral to the clockspring to the movable steering components so that the tape can operate within its designed travel limits and the SAS can accurately monitor and communicate steering wheel inputs. However, if the clockspring is removed from the steering column or if the steering shaft is disconnected from the steering gear, the clockspring spool and the SAS can change position relative to the movable steering components and relative to each other. The clockspring must be replaced if proper centering has been compromised or the tape may be damaged and Diagnostic Trouble Codes (DTC) or faults may be set within the SAS.

Service replacement clocksprings are shipped pre-centered and with a plastic locking pin installed. This locking pin should not be removed until the clockspring has been installed on the steering column. If the locking pin is removed before the clockspring is installed on a steering column, the clockspring must be replaced with a new unit. Proper clockspring installation must also be confirmed by viewing the SAS Menu Item, Data Display function using a diagnostic scan tool.

The hard wired clockspring circuits as well as the hard wired inputs and outputs of the SAS 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 SAS or the electronic controls or communication between other modules and devices that provide features of the Electronic Stability Program (ESP) or the Supplemental Restraint System (SRS). The most reliable, efficient, and accurate means to diagnose the SAS or the electronic controls and communication related to ESP or SRS operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.