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Part 2




Cruise Control Description and Operation (Adaptive Cruise Control)


Cruise Indicators and Messages

SERVICE RADAR CRUISE

The distance sensing cruise control (DSCC) module commands the display of the SERVICE RADAR CRUISE message in the driver information center (DIC) when it detects a malfunction in the Adaptive cruise control (ACC) System. The DSCC module sends a request to the instrument panel module (IPM) via the GMLAN serial data circuit to display the SERVICE RADAR CRUISE message in the DIC. The DIC displays the SERVICE RADAR CRUISE message when it receives a GMLAN serial data message request from the IPM. The SERVICE RADAR CRUISE is displayed in the DIC only when a diagnostic condition is present, the cruise switch is in On position and the vehicle speed is above 40 km/h (25 mph). When the message is displayed in the DIC the ACC System disengages. The DIC sounds an internal chime anytime it displays the SERVICE RADAR CRUISE message.

CRUISE NOT READY

The DSCC module commands the display of the CRUISE NOT READY message in the DIC when ACC cannot engage due to a temporary condition. The ACC vehicle conditions that prompt the display of the CRUISE NOT READY message are temporary and do not require service. If no target is identified by the radar at the time of vehicle ignition, the CRUISE NOT READY message will be displayed in the DIC until the radar is able to identify a target. CRUISE NOT READY message is also displayed in the DIC when the DSCC transceiver is too hot and the brakes are too hot. The DIC sounds an internal chime anytime it displays the CRUISE NOT READY message.

CLEAN RADAR

The CLEAN RADAR message displays in the DIC when the DSCC module detects a blockage of the radar. The radar may be blocked by snow, ice, dirt, heavy rain or road spray. In rare instances, a vertically misaligned radar may trigger the activation of the CLEAN RADAR message in the DIC. The DSCC module commands the display of the CLEAN RADAR message via a GMLAN serial data circuit request to the IPM. The DIC displays the CLEAN RADAR message when it receives a GMLAN serial data message request from the IPM. When the CLEAN RADAR message is displayed in the DIC, safely park the vehicle and turn OFF the ignition. Clean the front fascia cover to eliminate the blockage. It may also be necessary to clean both the outside surface of the cover, the inside surface of the cover and the DSCC module surface. Refer to Distance Sensing Cruise Control Maintenance (Procedures) for more cleaning information. It is important to turn the ignition OFF before cleaning any of the named surfaces. This is because the CLEAN RADAR message may still display in the DIC after cleaning the three surfaces. Cycling the ignition to OFF for 10 seconds is necessary to clear the CLEAN RADAR indicator if the indicator remains ON in the DIC. If the CLEAN RADAR indicator still remains ON after cleaning the radar and cycling the ignition, then the radar alignment will need to be checked and verified. Perform the Distance Sensing Cruise Control Aiming (Adjustments), if the radar is misaligned. The DIC sounds an internal chime anytime it displays the CLEAN RADAR message.

Cruise Engaged Indicator

The ACC engaged indicator is displayed in the head-up display (HUD) when the ACC is engaged by pressing the set/decrease switch. When the set/decrease switch is pressed by the driver, the IPM forwards the switch state to the engine control module (ECM) over the GMLAN serial data circuit. The ECM will use the switch input information from the IPM to determine the driver intended vehicle speed. The ECM communicates to the DSCC module over the GMLAN serial data circuit the ACC engaged state and the driver selected speed. When the DSCC module receives the ECM message indicating that ACC is active, the DSCC module commands the display of the ACC engaged indicator via a GMLAN serial data message to the IPM. The HUD displays the ACC engaged indicator when it receives a GMLAN serial data message from the IPM requesting the display. The driver may have to adjust the position of the HUD or the intensity of the display to see the information being displayed properly.

Set Speed

The ACC vehicle set speed is displayed at all times in the primary or secondary display of the HUD when ACC is engaged. The set speed is displayed in the primary HUD display for a few seconds after the initial engagement of ACC or a change in the set speed has just occurred. When, the set speed display time in the primary HUD display elapses, the set speed display is moved to the secondary HUD display. The set speed is also moved to the secondary display when a new ACC related message needs to be displayed. The DSCC module set speed display request is sent to the IPM via the GMLAN serial data circuit. The HUD displays the set speed when it receives a GMLAN serial data message from the IPM requesting the set speed displayed in the HUD. The HUD controls when the set speed is displayed in the primary or secondary HUD display.

Follow Distance

The HUD displays the driver selected following distance when ACC is engaged and the gap up/down switch is active. The current follow distance setting is displayed in the HUD for a few seconds after the gap up/down switch is pressed to increase or decrease the following distance. The DSCC module follow distance display request is sent to the IPM via the GMLAN serial data circuit. The HUD displays the follow distance when it receives a GMLAN serial data message from the IPM requesting the follow distance displayed in the HUD. The HUD will not display the follow distance if an indicator with a higher priority needs to be displayed in the HUD.

Vehicle Ahead Indicator

The vehicle ahead indicator is displayed in the HUD when the radar identifies an in-path vehicle. The vehicle ahead indicator is a warning to the driver that a vehicle is ahead within a distance of 100 meters (109.3 yards). The indicator also serves as a feedback to the driver that the radar is functioning properly. The DSCC module commands the display of the vehicle ahead indicator via a GMLAN serial data message to the IPM. The HUD displays the vehicle ahead indicator when it receives a GMLAN serial data message request from the IPM. The vehicle ahead indicator only displays with the ACC active and may sometimes display for stationary road objects.

Driver Alert

The driver alert indicator warns the driver of a certain road or vehicle conditions that require his attention. When the driver alert indicator flashes in the HUD it is accompanied by an audible warning from the audio amplifier. The driver alert indicator flashes in the HUD and the audible warning sounds when one of the following occurs:

* DSCC module is requesting maximum automatic braking.
* DSCC module automatic braking request not sufficient to safely stop the vehicle in certain road conditions.
* Cruise disengagement not initiated by driver or any driver action.
* Vehicle speed is below 32 km/h (20 mph)
* Abnormal cruise disengagement

The DSCC module requests the driver alert indicator and the audible warning via a GMLAN serial data message to the IPM. The IPM then sends a GMLAN serial data message to the HUD and to the audio amplifier requesting the driver alert indicator and the audible warning to be activated.

Cruise Engaged

The Adaptive Cruise Control (ACC) System will engage and adjust vehicle speeds based on the activation of the following cruise switches:

* On/off
* Set/decrease
* Resume/increase

ACC will not engage if any inhibit criteria is active. Also, the driver must step on the brakes at each ignition cycle before attempting to engage ACC. The engine control module (ECM) looks to the instrument panel module (IPM) for the brake initial travel achieved signal indicating that the driver has stepped on the brakes before attempting to engage ACC.

The vehicle speed must be above 40 km/h (25 mph) and below 188.3 km/h (117 mph) for the ACC System to be engaged. In the engaged state, the ACC System allows the driver to override the controlled vehicle speed temporarily while still remaining in the engaged state.

Cruise Inhibited

DSCC Module Inhibits

The distance sensing cruise control (DSCC) module inhibits the Adaptive Cruise Control (ACC) System when any of the following conditions exists:

* The RADAR NOT READY message is active in the DIC.
* Initial brake pedal travel signal from brake pedal position (BPP) sensor is not present
* An ACC System malfunction and/or failure is present.
* The CLEAN RADAR indicator is active in the DIC.
* An invalid vehicle speed
* The Antilock Brake System (ABS) is active during automatic braking.
* The Cruise Switch failed message from the instrument panel module (IPM) is sent to the DSCC module.
* Automatic braking failure-A GMLAN signal from the electronic brake control module (EBCM) the to DSCC module indicating an automatic braking failure
* A HUD failure condition is present.
* The HUD is not turned ON.
* The brakes overheated signal from ABS
* A head-up display (HUD) failure condition is present
* The ACC System audible warning is not present, due to an audio amplifier failure.
* The DSCC module transceiver temperature is hot.
* The ACC is not present-The ACC can be disabled through the IPM ACC disable feature.
* The driver applied brake pressure.

ECM Inhibits

The ECM inhibits the ACC System operation when any of the following conditions exists:

* The ACC inhibited signal from DSCC is present.
* The vehicle speed is less than 32.2 km/h (20 mph).
* The vehicle speed is greater than 193.1 km/h (120 mph).
* Automatic braking failure-A GMLAN signal from EBCM to the ECM indicating an automatic braking failure
* The ACC present signal from the IPM is false.
* The driver applied brake pressure.
* A cruise control switch failure is present.
* The park brake switch signal from the IPM is active.
* A Throttle Actuator Control (TAC) System failure is present.
* The Traction Control System (TCS) is active.
* The ABS is active.
* The engine speed protection is active.
* The vehicle speed protection is active.
* The engine speed is too high or too low.
* The automatic transmission is in first gear, Park, Neutral or Reverse.
* The initial brake pedal travel signal from the BPP sensor is not present.
* The system voltage is too low.

Cruise Disengaged

The Adaptive Cruise Control (ACC) System disengages when any of the following occurs:

* The driver depresses the brake pedal.
* The driver turns the ACC On/Off switch OFF.

Pressing the brake pedal while the ACC is engaged will disengage the ACC System.

Other Adaptive Cruise Control (ACC) Features

Mechanical Alignment

When the radar is out of alignment, DTC C1002 is set by the DSCC module. When DTC C1002 is set, it becomes necessary to mechanically align the radar using the special alignment tool. Refer to DTC C1002 (C1002). For further information on how to aim and align the radar, refer to Distance Sensing Cruise Control Aiming (Adjustments). An out of alignment condition may be as a result of tampering or damage to the DSCC module mounting structures or the adjuster settings. An out of alignment condition may also be as a result of damage to the front end of the vehicle or merely as a result of wear and tear. Refer to Distance Sensing Cruise Control Module Replacement (Removal and Replacement) on how to properly mount and adjust the DSCC module. Performance of the ACC System may be degraded after a DSCC module replacement. Normal vehicle driving will correct the performance of the ACC System.

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