Part 2

Set/Decrease Switch

The ACC System is engaged when the ACC On/Off switch is turned ON and the set/decrease switch is momentarily pressed and released. When the set/decrease switch is pressed, the selected vehicle speed is set to the current vehicle speed by the ECM. The vehicle speed must be at or greater than 48 km/h (30 mph). While in the engaged state, the selected vehicle speed and the following distance can be adjusted. Pressing and holding the set/decrease switch, when the ACC System is engaged, will decrease the selected vehicle speed without deactivating the ACC. Momentarily pressing and releasing the set/decrease switch, when the ACC is engaged, decreased the selected vehicle speed by 1.6 km/h (1 mph) for each time that the set/decrease switch is pressed.

Resume/Increase Switch

The resume/increase switch is used in order to increase the selected vehicle speed when ACC is active. The amount selected vehicle speed can be increased from the resume/increase switch depends on how long the switch is pressed. The presence of a slower moving vehicle in the path of the ACC vehicle will limit the extent to which the selected vehicle speed can be achieved. If there is no preceding vehicle in front, limiting the ACC vehicle acceleration, then the vehicle speed that is attained is the new selected vehicle speed. Acceleration is terminated when the resume/increase switch is released. Momentarily pressing and releasing the resume/increase switch will allow the selected vehicle to accelerate in at 1.6 km/h (1 mph) increments for each time that the resume/increase switch is momentarily pressed.

Gap Up/Down Switch

The gap up/down switch allows the driver to determine how closely the adaptive cruise control (ACC) vehicle follows a target vehicle while ACC is engaged. When the ACC vehicle speed is being limited due to a slower travelling vehicle, the ACC vehicle speed is automatically controlled to the follow speed limit. The gap switch has 6 following distance selections that range from 1-2 seconds. The gap switch following distance between the ACC vehicle and the target vehicle is expressed in time as opposed to actual distance. The distance maintained for a selected gap will vary based on vehicle speed. The faster the vehicle speed, the further back you will follow. The gap setting can only be adjusted when the ACC System is engaged. The gap up/down switch is hard-wired to the body control module (BCM) and voltage is provided to the switch from the BCM via the gap up/down ignition 1 voltage circuit. Based on voltage variations, the BCM is able to read the selected gap up/down switch selection and communicates the switch status on the serial data circuit to the distance sensing cruise control (DSCC) module. The gap up/down switch is a 3 position momentary switch-Center, Gap Up and Gap Down-with the following valid signal values:

* No Activation
* Increase Gap
* Decrease Gap

The initial push of the gap switch recalls the current setting and activates the display. Subsequent pushes of the gap switch will change the gap setting. Momentarily pressing the gap up/down switch will adjust the switch to the desired gap setting. When the voltage from the gap up/down switch circuit is in an invalid range, the BCM will default to increasing the gap value.

Cruise Indicators and Messages

SERVICE RADAR CRUISE

The 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 body control module (BCM) via the 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 serial data message request from the BCM. The SERVICE RADAR CRUISE is displayed in the DIC only when a diagnostic condition is present, the cruise switch is in the On position and the vehicle speed is above 48 km/h (30 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 serial data circuit request to the BCM. The DIC displays the CLEAN RADAR message when it receives a serial data message request from the BCM. 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 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 driver information center (DIC) when the ACC is engaged by pressing the set/decrease switch. When the set/decrease switch is pressed by the driver, the BCM forwards the switch state to the engine control module (ECM) over the serial data circuit. The ECM will use the switch input information from the BCM to determine the driver intended vehicle speed. The ECM communicates to the DSCC module over the 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 serial data message to the BCM. The HUD displays the ACC engaged indicator when it receives a serial data message from the BCM requesting the display.

Set Speed

The ACC vehicle set speed is displayed at all times in the DIC when ACC is engaged. The DSCC module set speed display request is sent to the BCM via the serial data circuit. The DIC displays the set speed when it receives a serial data message from the BCM requesting the set speed displayed. The DIC controls when the set speed is displayed.

Follow Distance

The DIC 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 DIC 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 BCM via the serial data circuit. The DIC displays the follow distance when it receives a serial data message from the BCM requesting the follow distance displayed in the DIC. The DIC will not display the follow distance if an indicator with a higher priority needs to be displayed in the DIC.

Vehicle Ahead Indicator

The vehicle ahead indicator is displayed in the DIC 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 serial data message to the BCM. The DIC displays the vehicle ahead indicator when it receives a serial data message request from the BCM. 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 DIC it is accompanied by an audible warning from the audio amplifier. The driver alert indicator flashes in the DIC 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 serial data message to the BCM. The BCM then sends a serial data message to the DIC 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 body control module (BCM) 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 at or above 48 km/h (30 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 driver information center (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 BCM is sent to the DSCC module.
* Automatic braking failure-a serial data message from the electronic brake control module (EBCM) the to DSCC module indicating an automatic braking failure
* The brakes overheated signal from ABS
* 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 BCM 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 at or less than 40 km/h (25 mph).
* The vehicle speed is greater than 193.1 km/h (120 mph).
* Automatic braking failure-a serial data message from EBCM to the ECM indicating an automatic braking failure
* The ACC present signal from the BCM is false.
* The driver applied brake pressure.
* A cruise control switch failure is present.
* The park brake switch signal from the BCM 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 distance sensing cruise control (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 adaptive cruise control (ACC) System may be degraded after a DSCC module replacement. Normal vehicle driving will correct the performance of the ACC System.