Module, Steering Column: Operation: Operation

WARNING: This page is about a different car, the 2014 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

Besides serving as the carrier for the clockspring, the left (lighting) multifunction switch and the right (wiper) multifunction switch, the Steering Column Control Module (SCCM) mounting housing contains an electronic circuit board, sometimes referred to as the Steering Control Module (SCM). The SCM is a Local Interface Network (LIN) bus master node and a gateway for the Controller Area Network (CAN) data bus. Refer to COMMUNICATION, DESCRIPTION . For additional information on the clockspring, refer to CLOCKSPRING, OPERATION . For additional information on the left multifunction switch, refer to SWITCH, MULTIFUNCTION, OPERATION . For additional information on the right multifunction switch, refer to SWITCH, MULTIFUNCTION, RIGHT, OPERATION .

The microcontroller based SCM provides power and ground to the multifunction switches, then utilizes integrated circuitry to monitor hard wired digital return inputs from the switches. Except for the circuits for the standard equipment Driver AirBag (DAB), which are pass-through circuits of the clockspring, the SCM also provides power and ground to all of the electronics carried on the steering wheel through the stand alone LIN module or, if the vehicle is so equipped, the LIN module integral to the speed control switch pod in the right horizontal steering wheel spoke. The stand alone LIN module or the integral LIN circuitry of the speed control switch pod are each a LIN slave node.

The steering wheel-mounted electronics monitored by the SCM include the horn switch, the standard equipment odometer switch pod, the optional equipment speed control switch pod, the remote radio switches, the optional hands-free communication switches and the optional Electronic Vehicle Information Center (EVIC) control switch pod. The LIN slave node monitors the changing states of these switches through both hard wired analog and digital return inputs, then communicates those switch states to the LIN master node circuitry of the SCM over the LIN data bus. In response to those inputs, the SCM CAN gateway circuitry then transmits electronic message outputs communicating all of the monitored switch state changes to other electronic modules in the vehicle over the CAN data bus.

The SCM is connected to a fused B(+) circuit and has a path to a clean ground at all times. These connections allow it to remain functional regardless of the ignition switch status. Any input to the SCM that controls a vehicle system function that does not require that the ignition switch status be On such as depressing the horn switch, prompts the SCM to wake up and transmit on the CAN data bus.

The Body Control Module (BCM) stores and compares vehicle configuration data with the SCM as well as with other Electronic Control Units (ECU) in the vehicle. This process is referred to as PRogramming Of Configuration of Systems Integrated (PROCSI) (also known as PROXI). If a configuration mismatch is detected, the BCM sets a DTC. A configuration mismatch DTC will require the performance of a Restore BCM PROXI Configuration routine, or a PROXI Configuration Alignment routine using a diagnostic scan tool.

The hard wired circuits between components related to the SCM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SCM or the electronic controls and communication between modules and other devices that provide some features of the SCM. The most reliable, efficient and accurate means to diagnose the SCM or the electronic controls and communication related to SCM operation requires the use of a diagnostic scan tool. Refer to DIAGNOSIS AND TESTING .