Subaru Ascent 2018-2026 Owner's Manual: BSD/RCTA approach indicator light/warning buzzer

When the BSD/RCTA system in the Subaru Ascent is active, it continuously monitors adjacent lanes and surrounding areas to enhance driver awareness. The BSD/RCTA approach indicator light provides a clear visual alert when another vehicle is detected traveling in a neighboring lane. In addition, when reversing the Subaru Ascent, both the indicator light and an audible warning buzzer work together to notify the driver if a vehicle is approaching from either the left or right side, helping reduce the risk of collisions during low-visibility maneuvers.

BSD/RCTA approach indicator light

BSD/RCTA approach indicator light

In the Subaru Ascent, these indicator lights are integrated into both exterior side mirrors, ensuring they remain within the driver’s natural field of view.

The indicator will illuminate steadily whenever the system detects a vehicle approaching from behind within the adjacent lane, providing early awareness of surrounding traffic.

The indicator light will begin flashing more noticeably to warn the driver of a potentially hazardous situation under the following conditions.

• If the indicator light is illuminated and the turn signal is activated toward the side where a vehicle has been detected.
• When reversing the Subaru Ascent and the system identifies an approaching vehicle from either side.

BSD/RCTA approach indicator light dimming function

To improve visibility and prevent glare at night, the Subaru Ascent automatically reduces the brightness of the BSD/RCTA indicator lights when the headlights are switched on.

NOTE

• Under certain lighting conditions, the BSD/RCTA indicator light in the Subaru Ascent may be more difficult to notice.
  • In strong direct sunlight
  • When bright headlights from vehicles behind shine directly onto the mirror
• If the illumination brightness control dial is set to its highest level, the dimming function may not reduce the brightness of the BSD/RCTA indicator light even when the headlights are on. For more details, refer to "Illumination brightness control".

BSD/RCTA approach warning buzzer (only when reversing)

During reversing, the Subaru Ascent enhances safety by combining visual alerts with an audible warning. The warning buzzer sounds simultaneously with the flashing indicator light whenever a vehicle is detected approaching from either side.

The volume level of this warning buzzer can be customized through the center information display, allowing drivers to tailor the alert intensity according to personal preference. Refer to "Car settings" for configuration details.

Safety tips regarding the BSD/RCTA approach indicator light/warning buzzer

• In certain driving situations, the BSD/RCTA system in the Subaru Ascent may respond with a slight delay or may not provide a warning at all.
  • When a vehicle quickly moves into the adjacent lane from a lane further away
  • When driving on steep inclines or on roads with frequent elevation changes
  • When crossing over mountain passes
  • When both your Subaru Ascent and another vehicle are positioned toward the outer edges of their respective lanes
  • When multiple vehicles are approaching closely one after another
  • When navigating tight curves or sharp turns at intersections
  • When there is a height difference between adjacent lanes
  • Immediately after activating the BSD/RCTA system via the "Rear Vehicle Detection (BSD/RCTA)" setting
  • Immediately after shifting the select lever into the "R" position
  • When the cargo area of the Subaru Ascent is heavily loaded, potentially affecting sensor performance
• When reversing, the BSD/RCTA alerts may also be delayed or limited in the following situations.
  • When backing out of angled or diagonal parking spaces
  • When a large vehicle is parked nearby, obstructing radar signal transmission
  • When reversing on inclined or uneven road surfaces
  • When reversing at higher speeds than recommended

The BSD/RCTA system in the Subaru Ascent is designed as a driver assistance feature to improve situational awareness. However, it does not replace the need for direct visual checks. Always confirm surroundings manually to ensure maximum safety while driving or reversing.

• While operating the Subaru Ascent, the BSD/RCTA approach indicator light may activate even when there is no vehicle nearby if you are driving close to large stationary objects such as guardrails, tunnel walls, concrete barriers, or roadside structures. These elements can reflect radar signals and be interpreted by the system as potential hazards.
• When turning at intersections, especially in dense urban environments or wide multi-lane junctions, the BSD/RCTA indicator light in the Subaru Ascent may briefly flash. This behavior is caused by the system detecting moving objects or reflecting surfaces around the intersection area.
• During reversing, if there are buildings, walls, or other large vertical surfaces behind the Subaru Ascent, the BSD/RCTA system may trigger both the flashing indicator light and the warning buzzer. This occurs because the radar sensors can interpret reflections as approaching objects, even when no moving vehicle is present.
• In certain driving scenarios, the BSD/RCTA system in the Subaru Ascent may detect vehicles that are actually two lanes away instead of directly adjacent. This can happen under the following conditions.
  • When your Subaru Ascent is positioned closer to the edge of its lane, reducing the effective separation between lanes from the sensor’s perspective
  • When a vehicle traveling two lanes away is also positioned near the inner edge of its lane, making it more visible to the radar sensors

These situations highlight how the advanced radar-based BSD/RCTA system in the Subaru Ascent prioritizes safety by reacting to potential risks, even if they are indirect or caused by environmental reflections. As a result, occasional unexpected alerts may occur, especially in complex surroundings. Drivers should remain attentive and use these alerts as supplementary assistance rather than relying on them as the sole source of situational awareness.

For best performance, keep the rear bumper area clean and free from dirt, ice, or obstructions, as this ensures that the Subaru Ascent BSD/RCTA sensors operate with maximum accuracy and reliability.