Adaptive Cruise Control
Adaptive Cruise Control
Refer to the Owner's Manual.
The Adaptive Cruise Control (ACC) is a combination of a speed and distance system. It relieves the driver from having to monitor the vehicle speed and the distance to the vehicle is front. The ACC slows down or speeds up the vehicle when the system detects a vehicle in front.
The following ACC functions on the Audi A8 were expanded: Vehicle speed range 0 to 250 km/h (0 to 155 mph), faster recognition of the vehicles moving in and out and reaction (using data from the lane change assistance, lane assist and the navigation system) Audi braking guard has also been expanded: Activation of the air spring damper and emergency blinking, braking, automatic partial and full braking, sending a signal to the seat belt tensioner and adaptive airbags.
The ACC works with video, radar and ultrasound. Vehicles 200 meters (218 yards) up ahead can be detected. When the driver must brake the vehicle, this will be automatically signaled.
The system can brake the vehicle to a complete stop in stop-and-go traffic and then start off again under certain conditions. Refer to the Owner's Manual.
The Audi A8 has two distance regulation control modules, the distance regulation control module (J428) and distance regulation control module 2 (J850). The distance regulation sensor and the distance regulation control module are installed in a single housing. If sensor/control module is faulty, entire unit must be replaced.
The distance regulation control module is located behind the right air intake grille in the front bumper.
The distance regulation control module 2 is located behind the left air intake grille in the front bumper.
In the following description, the sensor/control module unit is identified as the "sensor".
Malfunctions can occur due to contamination on the sensor. Remove the air intake grille in front of the sensor according to the repair information and clean the sensor.
The radar and ultrasound sensors must never be covered with stickers or paint because they will impair the function of the ACC and Audi braking guard.
Bumps or damage to the bumper cover, wheel housing can affect the distance regulation (ACC). This will cause the ACC to function improperly.
Before adjusting the ACC, check both "sensors" and their mounts and attachments for damage, external influences and secure fit. Repair any damaged components. Likewise, check the front bumper cover for damage, cracks and secure fit and service any damaged parts, if necessary.
Make sure the connector on the sensor is protected from dirt and water before disconnecting the connector. Take the correct measures, if needed.
Check the sensor for damage, contact corrosion and water before connecting the connector and service if necessary. General information for performing repairs to the vehicle electrical system.
Before performing ACC adjustment, Diagnostic Trouble Code (DTC) memory must be interrogated and malfunctions corrected.
The "adjustment angle measured value" from the ACC control module can tell if the sensor has been moved even just a little.
The ACC adjustment may only be set using a VW/Audi-approved wheel alignment tester and adjustment device!
A correct adjustment is required for perfect ACC function.
Before adjusting the ACC, see if the vehicle has a night vision system. If so, the camera for the night vision system must be calibrated first depending on the damage. After that both "sensors" can be adjusted.
• A new adjustment is necessary if:
• The rear axle toe was adjusted.
• The distance regulation control module (J428) and/or distance regulation control module 2 (J850) was removed and installed.
• The front bumper was removed and installed.
• The front bumper was loosened or moved.
• The front bumper is damaged.
• The adjustment angle is greater than -0.8° to +0.8°.
• The adaptive cruise control sensor was over adjusted vertically (leads to blind spot). Since the sensor has a limited view, its functions will likewise be limited and they cannot be attributed to dirt on the sensor or caused by the weather (for example, heavy rain or snow, ice on the sensor, etc.).