Speed Control - Service Information: Overview Dodge Dart PF

DESCRIPTION

An electronic speed control (also known as cruise control) system is available factory-installed equipment on this vehicle. The electronic speed control system includes the following major components, which are described in further detail elsewhere in this service information

1. Brake Lamp Switch - The brake (also known as stop) lamp switch is located on the brake pedal support bracket under the driver side of the instrument panel. Refer to «SWITCH, STOP LAMP, DESCRIPTION»(ref-646229-S17835487942014072800000) .
2. Speed Control Switch Pod - A speed control switch pod containing four momentary switch push buttons and an integral Local Interface Network (LIN) slave node is located in the right horizontal spoke of the steering wheel.
3. Wheel Speed Sensors - A wheel speed sensor is located on the knuckle of each front and rear wheel.

Certain functions and features of the speed control system rely upon resources shared with other electronic modules in the vehicle over a Local Interface Network (LIN) data bus as well as over the Controller Area Network (CAN) data bus. Other electronic modules in the vehicle that may affect speed control system operation are

1. Antilock Brake Module - An Antilock Brake Module (ABM) (also known as Controller Antilock Brake/CAB, Braking System Module/BSM or the Electronic Stability Control/ESC module) is located on the antilock brake Hydraulic Control Unit (HCU) in the engine compartment. Refer to «MODULE, ANTI-LOCK BRAKE SYSTEM, DESCRIPTION»(ref-646224-S38185183212014072800000) .
2. Instrument Cluster - A CRUISE indicator is located in the Instrument Cluster (IC) (also known as the Instrument Panel Cluster/IPC) that provides an amber indication to the vehicle operator when the speed control system is turned ON and not engaged, or a green indication when the speed control system is turned ON and engaged. Refer to «DESCRIPTION»(ref-646236-S08271057922014072800000) .
3. Powertrain Control Module - The Powertrain Control Module (PCM) (also known as the Engine Control Module/ECM) located in the engine compartment contains the software and hardware that monitors all of the speed control system inputs and controls all of the speed control system outputs. Refer to «MODULE, POWERTRAIN CONTROL, DESCRIPTION»(ref-646224-S10719748682014072800000) .
4. Steering Control Module - The Steering Control Module (SCM) is a Local Interface Network (LIN) master node and a gateway to the Controller Area Network (CAN) data bus. The SCM is integral and internal to the multi-function switch, which is integral to the Steering Column Control Module (SCCM) concealed beneath the steering column shrouds near the top of the steering column. Refer to «MODULE, STEERING COLUMN, DESCRIPTION»(ref-646224-S15426219732014072800000) .

The ABM, the SCM, the IC and the PCM each contain a microprocessor and programming that allow them to communicate with each other using the CAN data bus. This method of communication is used by the PCM for control of the CRUISE indicator in the IC. Refer to COMMUNICATION, DESCRIPTION .

Hard wired circuitry connects the electronic speed control system components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the speed control system components through the use of a combination of soldered splices, splice block connectors and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention as well as pin-out and location views for the various wire harness connectors, splices and grounds.

OPERATION

The vehicle operator controls all speed control system features through the speed control switch pod on the face of the right horizontal spoke of the steering wheel. When a push button of the switch pod is depressed, it provides a hard wired resistor multiplexed analog input to the Steering Control Module (SCM), which is a Local Interface Network (LIN) master node and a gateway to the Controller Area Network (CAN) data bus that is integral and internal to the multi-function switch near the top of the steering column.

The SCM reads the speed control switch input, then relays electronic speed control switch status messages to the Powertrain Control Module (PCM) (also known as the Engine Control Module/ECM) over the CAN data bus. The PCM software continually monitors these inputs as well as electronic vehicle distance message inputs from the Antilock Brake Module (ABM) (also known as the Controller Antilock Brake/CAB, the Brake System Module/BSM or the Electronic Stability Control/ESC module) and numerous hard wired inputs including the brake (or stop) lamp switch, then provides the appropriate electronic messages and hard wired outputs to invoke the requested and programmed electronic speed control features.

The PCM microprocessor continuously monitors all of the speed control system electrical circuits to determine the system readiness. If the PCM detects a monitored system fault, it sets and stores a Diagnostic Trouble Code (DTC). The PCM uses On-Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the diagnostic scan tool over the CAN data bus. This method of communication is used for control of the CRUISE indicator and the Malfunction Indicator Lamp (MIL) (also known as the Check Engine lamp) in the Instrument Cluster (IC) (also known as the Instrument Panel Cluster/IPC) and for system diagnosis and testing through the 16-way Data Link Connector (DLC) located on the driver side lower edge of the instrument panel.

The hard wired inputs and outputs for the SCM unit and the PCM 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 SCM, the PCM or the electronic controls or communication between other modules and devices that provide features of the speed control system. The most reliable, efficient, and accurate means to diagnose the SCM, the PCM or the electronic controls and communication related to speed control system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

The speed control switch pod is a resistor multiplexed unit that provides hard wired inputs to the microprocessor of the Steering Control Module (SCM), which is an electronics unit internal and integral to the multi-function switch. This electronics unit is both a Local Interface Network (LIN) master node and a Controller Area Network (CAN) gateway. The speed control switch pod also contains the circuitry of a LIN slave node, which provides source current for and communicates the switch or sensor states of the standard odometer switch pod, the optional Electronic Vehicle Information Center (EVIC) switch pod, the optional remote radio switches and the standard horn switch over the LIN data bus to the SCM.

The speed control switch pod contains four switch push buttons whose functions are

1. On/Off - This switch button enables or disables the speed control system and clears any previous speed control set speed from system memory.
2. Resume / + - This switch button restores the vehicle to a previously stored set speed or accelerates the vehicle from an already attained set speed.
3. Cancel - This switch button cancels the current speed control event, but does not turn the system OFF or clear the currently stored set speed.
4. Set / - - This switch button sets the current vehicle speed as the stored set speed or decelerates (coasts) the vehicle to a speed that is slower than the already attained set speed.

The SCM provides a clean ground and fused B(+) current for all of the switches and sensors on the rotating steering wheel through the LIN slave node circuitry of the speed control switch pod as well as for the Light Emitting Diode (LED) back lighting of both the speed control and the odometer or EVIC switch pods.

The SCM continually monitors all of the hard wired speed control switch circuits as well as the LIN bus data. The SCM will set a Diagnostic Trouble Code (DTC) for any problem it detects in the speed control switch circuits and will store a Signal Not Available (SNA) code for any LIN bus input errors. The SCM also communicates with other electronic modules over the Controller Area Network (CAN) data bus. Therefore, any DTC information can be retrieved using a diagnostic scan tool connected to the Data Link Connector (DLC).

The analog resistor multiplexed circuits of the speed control switch pod as well as the hard wired circuits between the switch pod and 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 LIN slave node, the SCM or the electronic controls and communication between modules and other devices that provide some features of the speed control system. The most reliable, efficient, and accurate means to diagnose the speed control switch pod, the LIN slave node, the SCM or the electronic controls and communication related to speed control system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.