Conventional Cruise Control
DESCRIPTION
The Cruise Control system is comprised of the following components:
| 1. | Refer to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . |
| 2. | Refer to POWERTRAIN CONTROL MODULE (PCM) . |
| 3. | Refer to BODY CONTROL MODULE (BCM) . |
| 4. | Refer to INSTRUMENT PANEL CLUSTER (IPC) . |
| 5. | Refer to STEERING COLUMN CONTROL MODULE (SCCM) . |
| 6. | Refer to CRUISE CONTROL SWITCH (CSWC) MODULE - This is the speed control switch pod located on the right steering wheel spoke. |
| - | Refer to CLUTCH POSITION SENSOR - Manual Transmission (MTX). |
| - | Refer to TRANSMISSION CONTROL MODULE (TCM) - Integral to the Automatic Transmission (ATX). |
OPERATION
Cruise Control
- The driver of the vehicle presses any of the cruise control specific buttons.
- The cruise control switch transits the request over the Local Interface Network (LIN) bus to the SCCM.
- The SCCM transmits this information over the Controller Area Network-Chassis (CAN-C) bus to the PCM.
- The PCM manages the algorithm in order to keep the vehicle speed set by the driver.
Active Speed Limiter
Active Speed Limiter is a function that allows the driver to set the vehicle speed limit. This function is set by the driver by interfacing with the CSWC button interface. The limiter function is active when the speed of the vehicle is equal to the limitation set point designated by the driver. If the driver exceeds this designated set point, the driver will be warned through audio and visual messages on the IPC. The driver is able to override the limiter function by pressing the accelerator pedal to speed the vehicle beyond the designated set point.
It is important to note that any vehicle driving system utilizing active torque requests (such as braking, traction, or stability events) will take precedence over and inhibit the active speed limiter and cruise control functions. Active speed limiting and cruise control will operate again once the torque request has been honored.
Active speed limiter and Hill Descent Control (HDC) are mutually exclusive and can not be active at the same time.
| Refer to COMPONENT INDEX . |
The ABS module is responsible for sending the following signals to the PCM:
Outputs
- Brake pedal activation
- Brake switch rationality
- Vehicle Speed Sensor (VSS) data
- Electronic Stability Control (ESC) state
- Park brake engagement
| Refer to COMPONENT INDEX . |
The BCM will gate the status of the cruise control system (ENGAGED or NOT ENGAGED) from the CAN-C to the CAN Interior High Speed (CAN-IHS) data network.
| Refer to COMPONENT INDEX . |
The Clutch position sensor is used on vehicles equipped with a MTX. The Clutch Position Sensor receives power and ground from the PCM. The PCM pulses the switch to read the clutch position over a dedicated line between the two components.
| Refer to COMPONENT INDEX . |
The CSWC module is a push button assembly that consists of five momentary push buttons: (ON/OFF, SET/-, SET/+, RESUME & CANCEL).
- On/Off - This is a momentary button that turns the system ON and OFF.
- SET/- button - This is a momentary switch that has three commands: Set, Tap Down and Decel (-), according to the push button activation mode and cruise control state.
- SET/+ button - This is a momentary switch that has three commands: Set, Tap Up and Accel (+), according to the push button activation mode and cruise control state.
- Resume - This is a momentary switch that allows the driver to re-engage cruise to the last stored vehicle speed, provided that the cruise control system is still enabled and current vehicle speed is greater than the minimum resume speed. When cruise control is disengaged, such that the system is still enabled & a valid set speed is stored, pulse or continuous activation of the Resume button will allow the driver to re-engage cruise control, resuming to the last stored set speed. Resume will only occur if a set speed has already been established.
- Cancel - This is a momentary switch that allows the driver to place cruise control in a disengaged state, yet keep the system enabled and the set speed stored.
The CSWC module monitors the states of the momentary push buttons (pressed/not pressed) and then transmits this information via the LIN to the SCCM.
If the vehicle is equipped with Engine Stop Start (ESS) system, the CSWC module will not reset during an ESS event. Instead, the CSWC module maintains cruise system functionality for the vehicle operator.
The CSWC receives its power, ground, LIN bus communication, and illumination from the SCCM.
| Refer to COMPONENT INDEX . |
The IPC performs three functions in relation to the cruise control system:
- Cruise control IPC display messages based on the current operating status
- Cruise control lamp indication based on the current system status
- Cruise controls "set speed" display according to the customers requested units
Inputs
- Set speed display signals from the PCM
- Multiple cruise control warning and status message requests from the PCM
| Refer to COMPONENT INDEX . |
The cruise control system and the active speed limiter function are managed by the PCM.
The PCM software continually monitors inputs from the SCCM, ABS module, and the TCM module along with numerous input signals. The PCM strategy then provides the appropriate electronic message outputs and hard wired outputs to operate the requested cruise control features.
The PCM monitors all of the cruise 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 using the CAN network data bus.
Inputs
- Brake pedal activation from the ABS module
- ESC from the ABS module
- Active Speed Limiter input from the SCCM
- Cruise Control inputs from the SCCM. The PCM monitors the CAN-C network every 10ms in order to prevent a missed button press
- VSS signal from the ABS module
- Park brake engagement signal from the ABS module
- Transmission limp mode input from the TCM. ATX only
- Clutch pedal position from the Clutch Position Sensor. Neutral position is detected by lack of correlation between engine and vehicle speed. This is for MTX vehicles only
Outputs
- Outputs to the IPC for message indication
- TCM to request down/up shifting
- State of the cruise control
- Power, ground, and a dedicated signal line to the Clutch Position Sensor
The PCM can inhibit or disengage cruise control when any of the following occur:
- CSWC button latched or stuck
- Brake pedal position or brake switch rationality errors
- Vehicle speed signal is not available
- TCM is in Limp Mode
- ESC fault detected
- Park brake engagement
- Drivetrain Control Module (DTCM) reports a 4 low engagement
- Invalid gear engagement detected
- Clutch switch rationality error
- Engine load sensor error (gas only)
- Fuel injection error
- Turbo sensor or actuator error
- Below minimum speed of 30 Kilometer Per Hour (KPH) or 18 Miles Per Hour (MPH)
- Engine Revolution Per Minute (RPM) is too high or reported as too high
- Throttle body actuator or sensor errors
- Accelerator Pedal Position Sensor (APPS) errors or errors in the accelerator pedal potentiometer.
The conditions that can turn off ASL are:
- CAN Message failure
- CRC failure
- Cruise Stuck Switch
- Vehicle Speed Signal Failure
- Accelerator Pedal Failure
| Refer to COMPONENT INDEX . |
The SCCM is the interface between the CSWC and the PCM. The CSWC evaluates the status of the CSWC buttons (pressed or not pressed) and then outputs this information to the SCCM. The SCCM takes this information from the LIN input and sends CAN-C cruise control request outputs to the PCM.
If the SCCM detected invalid signals or no signal from the CSWC, it will set a LIN based DTC on the CAN-C network.
Inputs
- Receives vehicle configuration indicating cruise and active speed limiter options are available on the vehicle
- LIN inputs from CSWC
Outputs
- Transmits the LIN CSWC inputs over the CAN-C network to the PCM
- Power and ground to the CSWC
- Illumination to the CSWC
| Refer to COMPONENT INDEX . |
The TCM receives inputs from the PCM for cruise control operation and performs requested down and up shifts when commanded.
When the vehicle is in manual shift mode, the transmission will not shift due to requests by the cruise system unless the transmission requires an upshift for the protection of powertrain components. For the vehicles equipped with transmission autostick or Electronic Range Selection (ERS) mode, the cruise system will not prevent the transmission from being manually shifted. The priority of different gear change requests is managed by TCM.
The cruise Resume function allows immediate downshifts based on current speed when the cruise Resume switch is pressed, by forcing a series of downshifts if the driver presses the Resume button and the vehicle is moving below the cruise control set speed. This will give the vehicle better acceleration to reach the set speed when the Resume button is pressed
Under downhill conditions, the PCM may require a transmission gear different from that selected by the transmission shift map, to maintain the cruise set speed. In these conditions, the PCM will transmit a maximum gear request to limit the operating range of the transmission. The transmission then will determine if selecting the maximum gear requested by the PCM can be honored, or would result in an engine overspeed condition, therefore not honoring the request from the PCM.
Inputs
- Presence of the cruise control system which indicates to the TCM that cruise is present on the vehicle
- Cruise control system operating state from the PCM
- Cruise set speed from the PCM over the CAN-C bus. This is to prevent unnecessary shifting
- Downshift request from the PCM over the CAN-C bus
Outputs
- Outputs the current transmission gear to the PCM
- Responds to gear change requests from the PCM
- Indication of Limp Mode to the PCM