Operation

OPERATION

The microprocessor-based Steering Control Module (SCM) (also known as the steering column module/MRM) utilizes integrated circuitry to monitor hard wired analog and multiplexed inputs from the multi-function switch, the horn switch, the optional speed control switch, the SAS and the optional steering wheel switches. In response to those inputs, the internal circuitry and programming of the SCM allow it to transmit electronic message outputs to other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. Operation.

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

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. For proper diagnosis of the SCM, the CAN data bus or the electronic communication related to SCM operation, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.