Diagnostic Aids

System Disabled possible reasons

• Switchable cruise control (if equipped): Verify the Adaptive Cruise Control is enabled by observing the corresponding indicator and message in the Driver Information Display. Switch between ACC and Regular Cruise Control by pressing and holding the Cancel switch
• B233B Radar Sensor Module - Long Range Mounting/Alignment: For (some) vehicles the "SERVICE DRIVER ASSIST SYSTEM" message can be displayed without a DTC being set, when the long range radar gets misaligned. Inspect the long range radar for proper mounting/alignment. In most cases, a mounting/alignment issue may be caused by a front end impact/collision that may or may not be obvious. Physically check the Long Range Radar Module bracket for damage and make sure it is in alignment. Place the vehicle on a level surface. Use an angle gauge/level to make sure the bracket is mounted 90 degrees (+/- 3 degrees). After the Long Range Radar Module alignment has been checked and/or corrected, perform the Radar Sensor Module - Long Range Learn 
• B174W Frontview Camera - Windshield Mounting: Inspect the front view camera sensor, on the windshield near the inside rearview mirror, to make sure it is attached properly to the windshield. Calibrate the front camera module after repair. Refer to Front View Camera Module Learn 
• Visually inspect the vehicle for any aftermarket add on equipment like bug deflectors, windshield tint/banners, grille emblems, push bars, license plates, etc. These items could block the radar / camera's view. Question the customer to see if this concern started after the installation of the aftermarket equipment. Remove any aftermarket items and retest system for proper operation.
• The radars and front camera are continuously monitoring for a blocked condition and if it determines its ability to "see" clearly is compromised, the radar/camera may become unavailable. When this occurs, the cruise will disengage and/or no cruise engagement with an "Adaptive Cruise:Temporarily Unavailable" message. Since the radars cannot visually "see" they rely on a complex blockage detection algorithm to predict blockage. Also, keep in mind that the front camera cannot see through objects or debris, so the camera can become visibly blocked. It is important to understand that disabling the adaptive cruise control, as a result of sensor blockage, is a normal function of the system and is intended to protect the driver from compromised system performance. Blockage detection is needed because if the radars/camera were/was truly blocked, the adaptive cruise control would not function properly.
• Foul weather: Foul weather such as snow, ice, heavy rain, road spray conditions may limit the sensors ability to "see". Also, a buildup of mud, snow, frost, dirt, bugs, etc on the windshield or front fascia can cause a blockage. This buildup can also occur on the back side of the fascia between the radar and back of fascia. One example, if the windshield has a buildup of frost/snow/ice which covers the front camera, the system may detect a blockage and disable the cruise. After the defroster warms the windshield and melts away the frost/snow/ice the system will become operational. This example may appear to be an intermittent issue.
• If driving in 4WD HI range (if equipped), adaptive cruise control will be disabled, which is normal. (Adaptive cruise control will function in Auto 4WD.)
• Dark Rural Areas: In very dark rural areas, the front view camera may detect blockage.
• Very High Ambient Temperatures: Very high ambient temperatures may affect camera operation.
• Barren Environments: As part of the blockage detection algorithm, the radar may conclude it is blocked if the radar does not "see" anything over a period of time. This can happen when driving in very bare environments, such as deserts and rural areas where there are no large objects to detect like other vehicles, bridges, building, trees, signs, mail boxes, guard rails, etc. Below is an example photo of an area where the radar may determine a blockage because there are no objects in the environment for the radar to "see". In these cases, if the system does not detect an object within approximately 60 seconds or 1.2 miles (2 km) the cruise will be disengaged and a "ADAPTIVE CRUISE TEMPORARILY UNAVAILABLE" message. If there were other vehicles on the road for the radar to detect there would not be any issues.