Description And Operation
DESCRIPTION
The Steering Column Control Module (SCCM) (1) is located at the top of the steering column just below the steering wheel. The SCCM includes the Steering Angle Sensor (SAS), the clockspring, the left (lighting) multifunction switch, and the right (wiper) multifunction switch.
The SCCM is secured to the steering column by an integral band clamp on the bottom of the instrument panel side of the SCCM. The SCCM has a centering attachment screw located on the top of the instrument panel side of the SCCM to be certain the SCCM is centered properly on the steering column.
There are also unique lugs cast into the outer circumference of the steering wheel hub that must be engaged into slots within the inner circumference of the clockspring rotor hub to unlock and drive both the clockspring and the SAS. The steering wheel fastener must be tightened to specification to ensure proper clockspring and SAS function.
The SCCM includes two integral connector receptacles that face toward the steering wheel (front side) and are connected to the steering wheel electrical components through two take outs and connectors of the steering wheel wire harness. The 12-way receptacle at the 9 o'clock position contains the circuits for the Local Interface Network (LIN) data bus to the Body Control Module (BCM), the LIN data bus to the SCCM (internal to the SCCM), the horn signal, B(+) with Positive Temperature Coefficient (PTC), and ground. The 2-way receptacle at the 3 o'clock position contains the circuits for the heated steering wheel (if equipped). Both radio control switches are hardwired to the Electronic Vehicle Information Center (EVIC) switch on the left steering wheel spoke, which then uses the LIN data bus to communicate with the BCM. The surface of the rotor hub facing the steering wheel (front side) also has three short pigtail wires with connectors. The pigtail connectors contain the circuits for the Driver AirBag (DAB).
The SCCM also includes two integral connector receptacles that face toward the instrument panel (back side) and are connected to the vehicle electrical system through two take outs and connectors of the instrument panel wire harness. The 14-way receptacle at the 6 o'clock position contains the circuits for heated steering wheel (if equipped) from the Heated Seat Module (HSM) and the DAB from the Occupant Restraint Controller (ORC) module. The 12-way receptacle at the 9 o'clock position contains the circuits for the LIN data bus to the BCM, the horn signal to the BCM, fused B(+), ground and the Controller Area Network - Chassis (CAN-C) data bus.
The SCCM cannot be adjusted or repaired. If ineffective or damaged, the entire SCCM must be replaced as a unit.
OPERATION
The SCCM includes an electronic circuit board with a microcontroller. The microcontroller is a LIN bus master node and a gateway for the CAN-C data bus. The SCCM microcontroller provides power and ground to the multifunction switches of the SCCM, then utilizes integrated circuitry to monitor hardwired analog and digital return inputs from each of these switches. Refer to COMMUNICATION, DESCRIPTION AND OPERATION . The circuits for the horn switch, the optional heated steering wheel and the standard equipment DAB are pass-through circuits of the SCCM. The steering wheel-mounted electronic functions monitored by the SCCM include the cruise switches. The output of the horn switch is hardwired to the BCM.
The switch pods (if equipped) in the left and right horizontal spokes of the steering wheel are each LIN bus slave nodes. The switch states of the hands free communication switches and the EVIC control switches in the left switch pod are communicated over the LIN bus directly to the LIN bus master node of the BCM. The left switch pod also controls the back lighting of both switch pods. The switch states of the speed control switches in the right switch pod are communicated over the LIN bus to the LIN master node of the SCCM. The internal circuitry of the SCCM gateway then relays electronic message outputs communicating those switch states; SAS, turn signal (1) and wiper (3) stalk transmit data to other electronic modules in the vehicle over the CAN-C data bus.
Two fixed connector receptacles (6 and 7) on the SCCM connect to the instrument panel wire harness via two wire harness connectors.
The SCCM is connected to a fused B(+) circuit from the Power Distribution Center (PDC) and receives a path to ground through a circuit in the body wire harness that is secured to the sheet metal behind the driver kick panel at all times. These connections allow it to remain functional regardless of the ignition switch status. Any input to the SCCM that controls a vehicle system function that does not require that the ignition switch status be ON such as pressing the horn switch, prompts the SCCM to wake up and transmit on the CAN-C data bus.
The service replacement SCCM is shipped with the clockspring (2) centered within the SCCM and with a plastic locking tab installed. This locking tab should not be removed until the SCCM has been properly installed on the steering column. If the locking tab is removed before the steering wheel is installed on a steering column, clockspring centering must be confirmed by viewing the inspection window on the clockspring rotor. If the black boxes of the clockspring tape are not visible in the inspection window, the entire SCCM must be replaced with a new unit. Proper clockspring installation may also be confirmed by viewing the SAS data using a diagnostic scan tool. Refer to MODULE, STEERING COLUMN CONTROL (SCCM), REMOVAL AND INSTALLATION .
For additional information about the wiper stalk functions, Refer to DESCRIPTION AND OPERATION .
For additional information about the lighting control stalk functions, Refer to DESCRIPTION AND OPERATION .
For additional information about the heated steering wheel controls, Refer to DESCRIPTION AND OPERATION .
For additional information about the SAS functions, Refer to DESCRIPTION AND OPERATION .