139 Stability system
Stability and Traction Control (
STC
) - Anti-spin system (option)
The
STC
system is designed to help reduce wheel spin by limiting power to the drive wheels if they begin to lose traction. At speeds over 25 mph (40 km/ h), the
STC
system monitors and compares all four wheels. If one of the drive (front) wheels shows any tendency to slip, such as when driving on slippery roads, the difference in speed is immediately detected. This triggers a signal to the engine management system, which will reduce engine torque (by reducing fuel) until the differential is corrected. This torque reduction is handled in stages, and reaction time is extremely fast. The system can be switched on or off by pressing the button on the center console for at least half a second (see page 38). The text window will briefly display "
STC
off" and the indicator light in the instrument panel will be ON when you have switched the system off. The
STC
system comes on each time you start your car.
The
STC
indicator light will come on for approximately 2 seconds when the engine is started as the system performs a self- diagnostic test.
This system should be switched off if you, for any reason, temporarily have to drive with tires of different dimensions (e. g., spare tire).
The symbol will flash when
STC
is actively regulating power to the drive wheels. Normal power may be reduced at this time. This is normal as power is momentarily reduced to help keep the drive wheels from losing traction and spinning.
If the
STC
system has been switched on using the button in the center console (the indicator light will normally go off) and the indicator light remains on, there is a fault in the system. In this case:
Stop the car in a suitable place and switch off the engine.
Restart the engine.
If the indicator light goes off, no further action is required.
If the light remains on, have the
STC
system inspected by an authorized Volvo retailer.
pg. 140 Stability system
Dynamic Stability Traction Control (
DSTC
) - option
The
DSTC
system performs all of the functions of the
STC
system. In addition,
DSTC
also applies the brakes to one or more of the wheels to help maintain stability if a wheel begins to lose traction. The system functions at speeds above 12 mph (20 km/ h) and works on all four wheels, on any road surface. When
DSTC
is active, brake pressure is regulated automatically and the brake pedal will move slightly. If you press the brake pedal while
DSTC
is automatically regulating brake pressure, the pedal will feel stiffer than normal. A pulsating sound will be audible at this time, which is quite normal.
Switching off
DSTC
DSTC
comes on each time you start your car, and should be left on at all times. If for any reason the steering wheel position or the front wheels are not properly aligned,
DSTC
should be switched off since the system may receive incorrect signals.
When the LED in the button is on, this indicates that
DSTC
is switched on (the light will also come on if a fault has been detected in the system). To avoid inadvertently switching the system off, the button must be pressed for at least half a second before
DSTC
is deactivated.
The text window will briefly display "
DSTC
off" and the symbol will come on to indicate that
DSTC
has been switched off. The system is automatically switched back on when the engine is restarted.
The
DSTC
indicator light will flash when:
DSTC
is actively functioning to help avoid loss of traction.
The
DSTC
indicator light will stay on when:
The car is started (for approximately 2 seconds as
DSTC
performs a self- diagnostic test).
DSTC
has been switched off by pressing the
DSTC
button in the center console (see page 38).
DSTC
has been temporarily switched off due to high brake temperature. The system will automatically switch on again when the brakes have cooled.
If the system has been switched off due to a fault. An authorized Volvo retailer should check the system.