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Tahoe / Yukon Service Manual

Active Safety System Description and Operation

The active safety system is a comprehensive feature set designed to help a driver avoid collisions or reduce crash damage while driving, backing, and parking. The K124 Image Processing Module is the primary controller for the active safety system. The active safety control module communicates on multiple serial data busses to share information with various control modules throughout the vehicle. The K124 Image Processing Module uses various sensors and control modules to monitor the vehicle surroundings and take deliberate action to avoid collisions or reduce crash damage. The active safety system tightly integrates the forward collision alert, adaptive cruise control, parking assist, and active emergency braking systems into a single cohesive system. The K124 Active Safety Control Module communicates via serial data on the object detection bus with the B174W Frontview Camera - Windshield and B233B Radar Sensor Module - Long Range to create a virtual fusion image of the area in front of the vehicle. The K124 Active Safety Control Module observes an actual visual image of the area directly ahead of the vehicle, within 60 m (197 ft), with the B174W  Frontview Camera - Windshield. The B233B Radar Sensor Module - Long Range is used to measure the distance to objects that are up to 200 m (656 ft) in front the vehicle. Within 60 m (197 ft) of the vehicle, all of these inputs are combined to create a fusion image of the area in front of the vehicle. At up to 200 m (656 ft), the B233B Radar Sensor Module - Long Range will detect and begin tracking objects immediately in front of the vehicle. Within 60 m (197 ft), the B174W Frontview Camera - Windshield will confirm objects that have been detected by the B233B Radar Sensor Module - Long Range. The fusion image created by the K124 Image Processing Module is used to detect collision risks and take action based on the immediacy of the risk. The a collision risk exists, the K124 Image Processing Module will alert the driver using the forward collision alert system. This will provide the driver with a visual and audible or haptic alert that a collision risk has been detected. If the driver does not take action to reduce the risk of collision, such as changing lanes or applying the brakes, the intelligent brake assist system will pre-fill the brake hydraulic system to reduce system response time and increase pressure when quickly applying the brakes. If a collision risk is imminent, the K124 Image Processing Module will enter automatic collision preparation, which will automatically apply the brakes in an effort to mitigate the collision or reduce collision damage. The K124 Image Processing Module communicates with the steering angle sensor (part of the K43 Power Steering Control Module) and the multi-axis acceleration sensor (part of the K36 Restraints Control Module) on CAN 1. These sensors are used to determine the intended vehicle path. Using the steering data and vehicle acceleration data, the K124 Image Processing Module will determine where the vehicle will be traveling and focus attention on objects in this path. An example would be a driver quickly changing lanes to avoid a collision. This would mitigate the collision risk in the previous lane and the K124 Image Processing Module would quickly transition to tracking objects for any collision risk in the new lane based on intended vehicle path. The K124 Image Processing Module also communicates with the K160 Brake System Control Module to instigate the braking functions of intelligent brake assist and automatic collision preparation. The Active Safety System analyzes data from the various control modules and sensors listed below: K124 Image Processing Module B174W Front View Camera - Windshield B233B Forward Range Radar Sensor - Long Range K182 Parking Assist Control Module K160 Brake System Control Module Component Description K124 Image Processing Module The K124 Image Processing Module analyzes data from various modules, sensors, and switches to provide enhanced safety features. In addition to providing alerts, the K124 Image Processing Module will provide driver assistance through integrated brake assist, automatic collision preparation, rear emergency braking, and adaptive cruise control. Inputs and outputs can either be connected directly to the K124 Image Processing Module or communicate though serial data. The K124 Image Processing Module communicates on CAN 1, CAN 2, and CAN 8. Forward collision alert, lane departure warning, and park assist alerts can be user selected to either a haptic signal utilizing the driver’s haptic signal motor seat or using beeps through the audio system. This setting can be found in the vehicle personalization menus. See the owner’s manual for more detailed information on vehicle personalization. If there is a DTC set in any of the modules that the K124 Image Processing Module uses as inputs, it will send a “Service Driver Assist” to the instrument cluster to alert the driver of a problem with the system. No other specific details are given unless the driver attempts to activate a specific system. For example if the driver attempts to turn on lane departure warning, the instrument cluster will display “Lane Departure Unavailable” and the indictor will flash and then go out. A scan tool must be used to read the DTCs that are causing the malfunction to help find the problem. Some of the inputs to the K124 Image Processing Module can affect forward facing features, rear facing features, or all features. Systems to check to determine which area to focus are rear park assist for rear features, and lane departure warning and adaptive cruise control for front features. If none of the active safety system features are operative, there may be an issue with another module on the vehicle not providing the proper data to the K124 Image Processing Module. If all K124 Image Processing Module features are inoperative, check the Adaptive Cruise Control Disable History Data, Lane Keep Assist Disable History Data, and Front Impact Mitigation Disable History Data in the scan tool for the reason for the malfunction. Definitions of parameters and suggestions on what to look for can be found in K124 Image Processing Module: Scan Tool Information. K124 Image Processing Module inputs: – B174W Front View Camera - Windshield – B233B Forward Range Radar Sensor - Long Range – K182 Parking Assist Control Module – Multi-axis acceleration sensor – Steering wheel angle sensor – Wheel speed sensors – Forward collision alert switch – Lane departure warning switch – Parking assist switch K124 Image Processing Module outputs: – K9 Body Control Module – K160 Brake System Control Module – K20 Engine Control Module – P16 Instrument Panel Cluster Control Module – P29 Head-Up Display – K40D Driver Seat Adjuster Memory Module – Lane keep assist switch indicator – Parking assist switch indicator – Infotainment system B174W Front View Camera - Windshield The B174W Front View Camera - Windshield is located behind the windshield, looking out at the road ahead and detects lane markings and objects directly ahead, within a distance of approximately 60 meters (197 ft). The B174W Front View Camera - Windshield is used for lane keep assist and forward collision alert systems. The B174W Front View Camera - Windshield communicates with the K124 Image Processing Module on CAN 8. Using information from the B174W Front View Camera - Windshield, the K124 Image Processing Module will provide forward collision alert and lane keep assist to the driver when appropriate. The alerts and warnings can be user-selected to be audible through the audio system or haptic using the active safety seat. B233B Forward Range Radar Sensor - Long Range The B233B Forward Range Radar Sensor - Long Range is located behind the front grille emblem and is used in the 30–200 m (98–656 ft) range. The B233B Forward Range Radar Sensor - Long Range communicates with the K124 Image Processing Module on CAN 8. In addition to the wiring harness ground, the module is grounded through the mounting bracket. K182 Parking Assist Control Module The K182 Parking Assist Control Module uses ultrasonic object sensors located in the fascias to provide distance measurements to nearby objects. The K182 Parking Assist Control Module communicates with the K124 Image Processing Module on CAN 1. K160 Brake System Control Module The K160 Brake System Control Module performs the braking activities of the active safety system. When requested by the K124 Image Processing Module, the K160 Brake System Control Module will prepare or apply the brakes as necessary in response to an imminent collision. Active Safety System Operation Forward Collision Alert The forward collision alert system is a convenience feature of the K124 Image Processing Module, B174W Front View Camera - Windshield, and B233B Forward Range Radar Sensor - Long Range that issues a warning to the driver when a potential collision risk exists. When the system detects a vehicle in the path ahead, the green vehicle ahead indicator is illuminated on the P16  Instrument Panel Cluster Control Module. If the vehicle ahead is being followed too closely, the vehicle ahead indicator will be amber. When approaching another vehicle too rapidly, the P43  Forward Collision Alert Display (without UV6) or collision alert symbol in the P29 Head-Up Display (with UV6) will flash. An audible alert sound will simultaneously sound or the safety alert seat will provide haptic feedback. The visual alert cannot be changed, but the driver can select between audible or haptic alerts in the vehicle personalization menus. Refer to the vehicle owner manual for more detailed information on vehicle personalization. Forward collision alert does not provide a warning to help avoid a crash unless it detects a vehicle. Forward collision alert may not detect a vehicle ahead if the B174W Front View Camera - Windshield is blocked by dirt, snow, or ice, or if the windshield is damaged. It may also not detect a vehicle on winding or hilly roads, or in conditions that can limit visibility such as fog, rain, or snow, or if the headlamps or windshield are not cleaned or in proper condition. Keep the windshield, headlamps, and B174W Front View Camera - Windshield area clean and in good repair. Forward collision alert may provide unnecessary alerts for turning vehicles, vehicles in other lanes, objects that are not vehicles, or shadows. These alerts are normal operation and the vehicle does not need service. Automatic Emergency Braking Automatic emergency braking system uses the K124 Image Processing Module, B174W Front View Camera - Windshield, and B233B Forward Range Radar Sensor - Long Range to determine if an imminent collision risk exists. If the brakes have not been applied, the system will automatically apply the brakes in an effort to mitigate the collision or reduce collision damage. The system has a detection range of approximately 60 m (197 ft) and will only function when a vehicle is detected, as indicated by the green vehicle ahead indicator is illuminated on the instrument cluster. Automatic emergency braking is not a substitute for normal vehicle braking and should not be relied on to brake the vehicle. Automatic emergency braking may not detect a vehicle ahead if the B174W Front View Camera - Windshield is blocked by dirt, snow, or ice, or if the windshield is damaged. It may also not detect a vehicle on winding or hilly roads, or in conditions that can limit visibility such as fog, rain, or snow, or if the headlamps or windshield are not cleaned or in proper condition. Keep the windshield, headlamps, and B174W Front View Camera - Windshield area clean and in good repair. Front Pedestrian Braking Front pedestrian braking system uses the K124 Image Processing Module, B174W Front View Camera - Windshield, and B233B Forward Range Radar Sensor - Long Range to determine if an imminent collision risk exists with a nearby pedestrian. If the brakes have not been applied, the system will automatically apply the brakes in an effort to avoid or reduce the harm caused by front-end crashes with nearby pedestrians. The system has a detection range of approximately 40  m (131 ft) and will only function when a pedestrian is detected, as indicated by the amber pedestrian detected indicator illuminated on the instrument cluster. Front pedestrian braking is not a substitute for normal vehicle braking and should not be relied on to brake the vehicle. Front pedestrian braking may not detect a pedestrian if the B174W Front View Camera - Windshield is blocked by dirt, snow, or ice, or if the windshield is damaged. It may also not detect a pedestrian on winding or hilly roads, or in conditions that can limit visibility such as fog, rain, or snow, or if the headlamps or windshield are not cleaned or in proper condition. Keep the windshield, headlamps, and B174W Front View Camera - Windshield area clean and in good repair. Backing Warning The backing warning system utilized the K124 Image Processing Module and the K182 Parking Assist Control Module to warn of rear objects when backing up at speeds greater than 8 km/h (5  mph). Utilizing the ultrasonic rear object sensors, the K182 Parking Assist Control Module can only detect object at speeds up to 8 km/h (5 mph). By utilizing the K124 Image Processing Module and B233CR Short Range Radar Sensor - Rear Middle, along with the K182 Parking Assist Control Module and the rear object sensors, object can be detected at speeds greater than 8 km/h (5  mph). While reversing at speeds greater than 8 km/h (5 mph), the backing warning system will alert the driver with an audible alert or through haptic feedback from the safety alert seat when an object is first detected. If the system detects a potential collision risk, a series of audible beeps or haptic feedback pulses will be provided, as well as a quick pulse of the brakes. Reverse Automatic Braking The rear automatic braking system is designed to help avoid or reduce the harm caused by backing crashes. If the system detects the vehicle is backing too fast to avoid a collision, it may automatically brake hard to a stop. Utilizing the K124 Image Processing Module and the K182 Parking Assist Control Module, rear automatic braking attempts to avoid imminent collision by automatically braking the vehicle when traveling in reverse. In conjunction with the backing warning system, if the driver does not respond to the audible and haptic alerts while reversing, the system will automatically brake the vehicle to a stop. Rear automatic braking also prevents the vehicle from backing into an object if the vehicle is stopped and shifted to R. If the system detects an object immediately behind the vehicle while attempting to reverse from a stop, the brakes will be applied. Pressing the brake pedal after the vehicle comes to a stop will release the rear automatic braking. It may be necessary to release the electronic parking brake. When it is safe to do so, pressing the accelerator pedal firmly at any time will override the rear automatic braking. If rear automatic braking is active and there is no object behind the vehicle, make sure there is no snow, ice, or debris on the rear object sensors. Lane Keep Assist The lane keep assist system is a convenience feature that utilizes the B174W Front View Camera - Windshield and K124 Image Processing Module to determine if the vehicle has unintentionally crossed a lane marking and issue a warning. The B174W Front View Camera - Windshield is located behind the windshield, looking out at the road ahead and detecting any lane markings. When the vehicle unintentionally leaves a detected lane, visual and audible or haptic alerts are given to the driver. The visual alert cannot be changed, but the driver can select between audible or haptic alerts in the vehicle personalization menus. Refer to Lane Keep Assist Description and Operation for more information about the Lane Keep Assist function.