2015 VOLVO XC90 brake

DRIVER SUPPORT
268
Other Adaptive Cruise Control (ACC) functionsACC is an optional system designed to assist
the driver by maintaining a set speed or a set time interval to the vehicle ahead.
ACC has several supplementary functions:
• Changing target vehicles
• Automatic standby mode when changing tar- gets
• Auto-hold brake function
• Deactivation of the auto-hold brake function
• Automatically setting the parking brake
Changing target vehicles
If the target vehicle turns suddenly, there may be a sta- tionary vehicle ahead
When ACC is actively following another vehicle at speeds
under 20 mph (30 km/h) and changes
targets from a moving vehicle to a stationary one, the system will brake for the stationary vehicle.
WARNING
If ACC changes targets from a moving vehicle to a stationary one at speeds above 20 mph
(30 km/h), the system will not react to the
stationary vehicle and will accelerate to the previously set speed. The driver must actively apply the brakes to slow/stop the vehicle.
Automatic standby mode when changing targets
ACC disengages and goes into standby mode if:
• your vehicle's speed goes below approx. 3 mph (5 km/h) and ACC cannot determine ifthe target object is a stationary vehicle orsome other type of object such as a speedbump, etc
• the vehicle's speed goes below approx.3 mph (5 km/h) and the vehicle aheadchanges lanes or turns so that ACC nolonger has a target vehicle to follow
Auto-hold brake functionIn slow-moving, stop-and-go traffic or when stop- ped at a traffic light, driving will resume automati-cally if the vehicle is not stopped for more thanapprox. 3 seconds. If it takes more than3 seconds for the vehicle ahead to begin movingagain, ACC will go into standby mode and theauto-hold brake function will activate.
–The driver will then have to reactivate ACC in one of the following ways:
• Press the
button on the left-side
steering wheel keypad
• Press the accelerator pedal
> ACC will resume following the vehicle ahead (target vehicle) if it begins to move
within approx. 6 seconds.
NOTE
ACC can keep the vehicle at a standstill for up to 5 minutes, after which the parking brakewill be set and ACC will go into standbymode. The parking brake has to be released before ACC can be reactivated.

DRIVER SUPPORT
* Option/accessory, for more information, see Introduction.269
Deactivation of the auto-hold brake
function
In certain situations, auto-hold will be deactivated when the vehicle is at a standstill and ACC will gointo standby mode. This means that the brakes will be released and the vehicle can begin to roll. The driver must actively apply the brakes to keep the vehicle at a standstill. This can occur in the following situations: • the driver presses the brake pedal
• the parking brake is set
• the gear selector is moved to the
P, N or R
positions
• the driver puts ACC in standby mode
Automatically setting the parking brakeIn certain situations, the parking brake is set automatically to help keep the vehicle at a stand-still. This occurs if:
• the driver unbuckles the seat belt or opens the door
• ACC has kept the vehicle at a standstill formore than approx. 5 minutes
• the engine is turned off
• the brakes overheat
Related information
•
Adaptive Cruise Control (ACC)
* (p. 252)
• Auto-hold brake function (p. 332)
• Parking brake (p. 335)
Radar sensor
The radar sensor is used by several driver sup- port functions to help detect other vehicles.
The radar sensor is used by the following func- tions:
• Distance Alert
*
• Adaptive Cruise Control
*
• Pilot Assist
*
• City Safety
*
Modification of the radar sensor could make itsuse illegal.
Related information
• Radar sensor - type approval (p. 270)
• Radar sensor limitations (p. 245)

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273
City Safety™
City Safety ™ is a support system designed to
help alert the driver to pedestrians, cyclists and vehicles that may appear suddenly in front ofyour vehicle. Visual and audible alerts are provi-ded. The vehicle will brake automatically if thedriver is unable to react quickly enough.
City Safety introduction
Location of the camera and radar sensor
City Safety can help prevent a collision or lower the vehicle's speed at the point of impact.
WARNING
• City Safety
™ is a supplemental aid to the
driver. It can never replace the driver

DRIVER SUPPORT
274When triggered, City Safety carries out three steps in the following order: 1.
Collision warning
2. Brake assistance
3. Auto-brake
1: Collision warningThe driver is first alerted to the risk of an immi- nent collision. City Safety can detect pedestrians, cyclists or vehicles that are stationary or that are moving inthe same direction as your vehicle. The driver isalerted by a flashing red warning signal, an audi-ble signal and pulsations in the brake pedal.
2: Brake assistanceIf the risk of a collision increases, brake supportwill be activated. This function increases pressure on the brake pedal if the driver does not apply enough pres-sure to the pedal.
3: Auto-brakeThe brakes will be applied automatically. If the driver has not taken action at this stage and a collision is imminent, auto-braking will be trig-gered. Full braking effect will be used to avoidthe collision if possible or to make the speed atthe point of impact as low as possible. In certain situations, auto-braking may begin with limited effect before full braking is used. If City Safety has prevented a collision, the vehi-cle will be kept at a standstill until the drivertakes action. If the vehicle has slowed to avoidcolliding with the vehicle ahead, your speed willbe reduced to that vehicle's speed. When auto-break is triggered, the seat belt pre- tensioners may also be activated, see the article"Seat belts" for additional information. Auto-braking can be cancelled if the driver presses hard on the accelerator pedal. When City Safety applies the brakes, the brake lights will illuminate. When City Safety is triggered and applies the brakes, a text message will be displayed in theinstrument panel.
WARNING
Warnings will only be provided if there is an imminent risk of a collision taking place. Thedriver should be aware of the system's limita-tions before operating the vehicle. Warnings for pedestrians and cyclists will not be provided if the vehicle's speed is above50 mph (80 km/h). City Safety's auto-brake function can help prevent a collision or reduce the speed atwhich a collision occurs. However, the drivershould always apply the brakes, even if auto-brake is operating. The driver is always responsible for maintain- ing the correct speed and distance in relationto the vehicle ahead. Never wait for a collisionwarning or for City Safety to intervene. City Safety maintenance may only be carried out by a trained and qualified Volvo servicetechnician.
Related information
•
City Safety
™ troubleshooting (p. 280)
• City Safety in crossing traffic (p. 277)
• City Safety limitations (p. 278)
• City Safety symbols and messages (p. 282)
• Detecting cyclists and pedestrians with City Safety (p. 275)
• Rear Collision Warning (RCW) (p. 277)
• City Safety warning level settings (p. 275)

DRIVER SUPPORT
275
City Safety warning level settingsCity Safety is always activated but the function's warning distance can be adjusted.
NOTE
City Safety cannot be turned off and activates automatically each time the engine is started.
Setting a warning level (distance)The distance set for warnings determines the system's responsiveness and sets the distance atwhich visual, audible and tangible (haptic) warn-ings will be triggered. If the driver feels that warnings are given too often, the warning level can be lowered. Thismeans that warnings will be provided later, result-ing in fewer warnings being given. To do so:1. Tap
Settings in the center display's Top
view.
2. Tap
My CarIntelliSafeCity Safety.
3. Choose among
Earlier, Normal or Later.
Begin by choosing
Earlier. If too many warnings
are given, change to Normal.
The setting
Later should only used in exceptional
circumstances, e.g., for a more dynamic driving style.
WARNING
• No automatic system can be guaranteed to function 100% correctly in all situa-tions. For that reason, never test CitySafety by driving toward a person orobject. This could result in serious injuryor death.
• Even if the setting
Earlier has been
selected, warnings may be perceived as being given late, e.g., if the difference inspeed is great or if the vehicle aheadbrakes suddenly.
• City Safety can provide a warning for apotential collision but it can never shortenthe driver's reaction time.
• To help make City Safety as effective as possible, always using the setting
Earlieris recommended.
Related information
•City Safety limitations (p. 278)
• City Safety
™ (p. 273)
• Rear Collision Warning (RCW) (p. 277)
Detecting cyclists and pedestrians with City Safety
City Safety can detect vehicles, cyclists and pedestrians.
VehiclesCity Safety detects most types of vehicles that are either stationary, moving in the same direc-tion as your vehicle or approaching when you areabout to turn left. In order for City Safety to detect a vehicle in darkness, its headlights and taillights must be onand clearly visible.
Cyclists
Optimal example of what the system considers to be a cyclist: clear body/bike contours
To help function optimally, City Safety's function for cyclist detection needs clear informationabout the bike itself and the rider's head, arms,

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277
City Safety in crossing traffic
City Safety can help the driver when making a left turn in an intersection.
Turning at an intersection
1. The area in which City Safety can detect an oncoming vehicle
In order for City Safety to detect an approaching vehicle in situations where there is a risk of a col-lision, that vehicle must be within City Safety'srange (the red area in the illustration). The following criteria must also be met:
• your vehicle's speed must be at least 3 mph (4 km/h)
• the approaching vehicle's headlights must beon
WARNING
•
City Safety is a supplementary driving aid and does not function in all driving situa-tions or in all traffic, weather or road con-ditions.
• Warnings and braking for an approachingvehicle will usually come at a very latestage.
• The driver is responsible for maintaining asafe distance and speed. Never wait for awarning or for City Safety to take action.
LimitationsIn certain situations, it may be very difficult for City Safety to help the driver avoid a collision withan approaching vehicle in crossing traffic, forexample:
• on slippery roads when Electronic Stability Control is active
• if the approaching vehicle is detected at alate stage
• If the approaching vehicle is partiallyobscured by another vehicle
• if the approaching vehicle moves erratically(e.g., sudden lane changes at a late stage)
Related information
•
City Safety
™ (p. 273)
• City Safety limitations (p. 278)
Rear Collision Warning (RCW)
The
Rear Collision Warning with braking at
standstill (RCW) function can help the driver
avoid rear-end collisions.
RCW is activated automatically each time the engine is started and cannot be turned off. RCW can warn the driver of a vehicle approach- ing yours from behind by rapidly flashing yourrear turn signals. RCW is only activated when a vehicle is rapidly approaching your vehicle from behind. At speeds below 20 mph (30 km/h), if RCW determines that your vehicle is at risk of a rear-end collision, the front seat belt pretensionersand the Whiplash Protection System are acti-vated. Just prior to the collision, the brakes are also applied to help reduce your vehicle's forwardmovement if and when the collision occurs. How-ever, this can only happen if your vehicle is sta-tionary. The brakes will be released immediately if the accelerator pedal is pressed.

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278
NOTE
•Due to local traffic regulations in certain markets, RCW will
not activate the rear
turn signals. That part of the function will be deactivated.
• The use of the rear turn signals will alsobe deactivated if the City Safety warning level is set at
Later. See also the section
"Setting a warning level (distance)" in the article "City Safety settings."
• If RCW detects a vehicle approachingfrom behind, the seat belt pretensionersand Whiplash Protection System will beactivated.
LimitationsIn some circumstances, it may be difficult for RCW to help the driver if there is a risk of a colli-sion, such as: •
In slippery conditions when Electronic Stability Control is active
• If the vehicle approaching from the rear isdetected at a late stage
• If the vehicle approaching from the rearchanges lanes at a late stage
• If the vehicle approaching from the rear ismoving at a speed above approx. 50 mph(80 km/h) detected at a late stage
Related information
•
City Safety
™ (p. 273)
• Whiplash protection system (p. 89)
• Seat belts (p. 58)
• City Safety warning level settings (p. 275)
City Safety limitations
City Safety ™ may have limited or reduced func-
tionality in certain situations.
The function has several limitations that the driver should be familiar with:
Low objectsHanging objects, such as flags for overhanging loads or accessories such as auxiliary lights orfront protective grids that extend beyond theheight of the hood may limit City Safety's func-tion.
Slippery driving conditionsThe extended braking distance on slippery roads may reduce City Safety's capacity to help avoid acollision. In situations of this type, the ABSbrakes and Electronic Stability Control will helpprovide braking power and stability.
BacklightingStrong sunlight, reflections, extreme light con- trasts, the use of sunglasses, or if the driver is notlooking straight ahead may make the visual warn-ing signal in the windshield difficult to see.

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City Safety symbols and messages
A number of City Safety-related messages may be displayed in the instrument panel.
SymbolMessageExplanation
City Safety City Safety was activatedWhen City Safety is braking or has applied the brakes, one of more symbols may illuminate in the instrument panel and a text message will be displayed.
City Safety Reduced functionality Service requiredThe system is not functioning properly. Contact a trained and authorized Volvo service technician.
Related information
• City Safety
™ (p. 273)