2020 TOYOTA PRIUS PRIME Owners Manual (in English)

489
PRIUS PRIME_OM_OM47C77U_(U)
5-5. Using the driving support systems
5
Driving
Driving assist systems
◆ECB (Electronically Controlled Brake System)
The electronically controlled system generates braking force co rre-
sponding to the brake operation
◆ABS (Anti-lock Brake System)
Helps to prevent wheel lock when the brakes are applied suddenl y,
or if the brakes are applied while driving on a slippery road surface
◆Brake assist
Generates an increased level of braking force after the brake p edal
is depressed when the system de tects a panic stop situation
◆VSC (Vehicle Stability Control)
Helps the driver to control skidding when swerving suddenly or
turning on slippery road surfaces.
◆Enhanced VSC (Enhanced Vehicle Stability Control)
Provides cooperative control of the ABS, TRAC, VSC and EPS.
Helps to maintain directional stability when swerving on slippe ry
road surfaces by controlling steering performance.
◆TRAC (Traction Control)
Helps to maintain drive power and prevent the drive wheels from
spinning when starting the vehicl e or accelerating on slippery roads
To keep driving safety and perf ormance, the following systems
operate automatically in respon se to various driving situations.
Be aware, however, that these systems are supplementary and
should not be relied upon too heav ily when operating the vehi-
cle.

490
PRIUS PRIME_OM_OM47C77U_(U)
5-5. Using the driving support systems
◆Hill-start assist control
Helps to reduce the backward movement of the vehicle when start -
ing on an uphill
◆EPS (Electric Power Steering)
Employs an electric motor to reduce the amount of effort needed to
turn the steering wheel.
The slip indicator light will flash
while the TRAC/VSC/ABS sys-
tems are operating.
If the vehicle gets stuck in mud, dirt or snow, the TRAC system may
reduce power from the hybrid system to the wheels. Pressing to
turn the system off may make it easier for you to rock the vehicle in
order to free it.
To turn the TRAC system off,
quickly press and release .
The “Traction Control Turned Off”
will be shown on the multi-informa-
tion display.
Press
again to turn the sys-
tem back on.
When the TRAC/VSC/ABS systems are operating
Disabling the TRAC system

PRIUS PRIME_OM_OM47C77U_(U)
4915-5. Using the driving support systems
5
Driving
■Turning off both TRAC and VSC systems
To turn the TRAC and VSC systems off, press and hold for more than 3
seconds while the vehicle is stopped.
The VSC OFF indicator light will come on and the “Traction Cont rol Turned
Off” will be shown on the multi-information display.
*
Press again to turn the systems back on.
*: Pre-collision brake assist and pre-collision braking will also be disabled.
The PCS warning light will come on and the message will be show n on the
multi-information display. ( P. 6 6 3 )
■ When the message is displayed on the multi-information display show-
ing that TRAC has been disab led even if has not been pressed
TRAC is temporary deactivated. If the information continues to show, contact
your Toyota dealer.
■ Operating conditions of hill-start assist control
When the following four conditions are met, the hill-start assi st control will
operate:
● The shift position is in a position other than P or N (when sta rting off forward/
backward on an upward incline)
● The vehicle is stopped
● The accelerator pedal is not depressed
● The parking brake is not engaged
■ Automatic system cancelation of hill-start assist control
The hill-start assist control will turn off in any of the following situations:
● Shift the shift position to P or N
● The accelerator pedal is depressed
● The parking brake is engaged
● No more than 2 seconds have elapsed after the brake pedal is re leased.
■ Sounds and vibrations caused by the ABS, brake assist, VSC, TRAC and
hill-start assist control systems
●A sound may be heard from the engine compartment when the brake pedal
is depressed repeatedly, when the hybrid system is started or just after the
vehicle begins to move. This sound does not indicate that a mal function has
occurred in any of these systems.
● Any of the following conditions may occur when the above system s are
operating. None of these indicates that a malfunction has occur red.
• Vibrations may be felt through the vehicle body and steering.
• A motor sound may be heard also after the vehicle comes to a s top.

492
PRIUS PRIME_OM_OM47C77U_(U)
5-5. Using the driving support systems
■ECB operating sound
ECB operating sound may be heard in the following cases, but it does not
indicate that a malfunction has occurred.
● Operating sound heard from the engine compartment when the brak e pedal
is operated.
● Motor sound of the brake system heard from the front part of th e vehicle
when the driver’s door is opened.
● Operating sound heard from the engine compartment when one or t wo min-
utes passed after the stop of the hybrid system.
■ EPS operation sound
When the steering wheel is operated, a motor sound (whirring so und) may be
heard. This does not indicate a malfunction.
■ Automatic reactivation of TRAC and VSC systems
After turning the TRAC and VSC systems off, the systems will be automati-
cally re-enabled in the following situations:
● When the power switch is turned off
● If only the TRAC system is turned off, the TRAC will turn on wh en vehicle
speed increases
If both the TRAC and VSC systems are turned off, automatic re-e nabling
will not occur when vehicle speed increases.
■ Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the s ystem from
overheating when there is frequent steering input over an exten ded period of
time. The steering wheel may feel heavy as a result. Should thi s occur, refrain
from excessive steering input or stop the vehicle and turn the hybrid system
off. The EPS system should return to normal within 10 minutes.
■ Electric power steering system wa rning light (warning buzzer)
P. 663

PRIUS PRIME_OM_OM47C77U_(U)
4935-5. Using the driving support systems
5
Driving
WARNING
■The ABS does not operate effectively when
● The limits of tire gripping performance have been exceeded (such as
excessively worn tires on a snow covered road).
● The vehicle hydroplanes while driving at high speed on wet or s lick roads.
■ Stopping distance when the ABS is operating may exceed that of nor-
mal conditions
The ABS is not designed to shorten the vehicle’s stopping distance. Always
maintain a safe distance from the vehicle in front of you, especially in the
following situations:
● When driving on dirt, gravel or snow-covered roads
● When driving with tire chains
● When driving over bumps in the road
● When driving over roads with potholes or uneven surfaces
■ TRAC/VSC may not operate effectively when
Directional control and power may not be achievable while driving on slip-
pery road surfaces, even if the TRAC/VSC system is operating. D rive the
vehicle carefully in conditions where stability and power may be lost.
■ Hill-start assist control does not operate effectively when
● Do not overly rely on hill-start assist control. Hill-start ass ist control may
not operate effectively on steep inclines and roads covered wit h ice.
● Unlike the parking brake, hill-start assist control is not inte nded to hold the
vehicle stationary for an extended period of time. Do not attempt to use
hill-start assist control to hold the vehicle on an incline, as doing so may
lead to an accident.
■ When the TRAC/ABS/VSC is activated
The slip indicator light flashes. Always drive carefully. Reckless driving may
cause an accident. Exercise particular care when the indicator light flashes.

494
PRIUS PRIME_OM_OM47C77U_(U)
5-5. Using the driving support systems
WARNING
■When the TRAC/VSC systems are turned off
Be especially careful and drive at a speed appropriate to the r oad condi-
tions. As these are the systems to help ensure vehicle stability and driving
force, do not turn the TRAC/VSC systems off unless necessary.
■ Replacing tires
Make sure that all tires are of the specified size, brand, trea d pattern and
total load capacity. In addition, make sure that the tires are inflated to the
recommended tire inflation pressure level.
The ABS, TRAC and VSC systems will not function correctly if different tires
are installed on the vehicle.
Contact your Toyota dealer for further information when replaci ng tires or
wheels.
■ Handling of tires and the suspension
Using tires with any kind of problem or modifying the suspensio n will affect
the driving assist systems, and may cause a system to malfunction.

495
PRIUS PRIME_OM_OM47C77U_(U)
5-6. Driving tips
5
Driving
Winter driving tips
●Use fluids that are appropriate t o the prevailing outside tempera-
tures. • Engine oil
• Engine/power control unit coolant
• Washer fluid
● Have a service technician inspect the condition of the 12-volt bat-
tery.
● Have the vehicle fitted with four snow tires or purchase a set of tire
chains for the front tires.
Ensure that all tires are the same size and brand, and that cha ins match
the size of the tires.
Perform the following accordi ng to the driving conditions:
● Do not try to forcibly open a window or move a wiper that is fr ozen.
Pour warm water over the frozen area to melt the ice. Wipe away
the water immediately to p revent it from freezing.
● To ensure proper operation of the climate control system fan,
remove any snow that has accumulated on the air inlet vents in
front of the windshield.
● Check for and remove any excess ic e or snow that may have accu-
mulated on the exterior lights, vehicle’s roof, chassis, around the
tires or on the brakes.
● Remove any snow or mud from the bottom of your shoes before
getting in the vehicle.
Carry out the necessary preparations and inspections before
driving the vehicle in winter. Always drive the vehicle in a ma n-
ner appropriate to the prevailing weather conditions.
Preparation for winter
Before driving the vehicle

496
PRIUS PRIME_OM_OM47C77U_(U)
5-6. Driving tips
Accelerate the vehicle slowly, keep a safe distance between you and
the vehicle ahead, and drive at a reduced speed suitable to roa d con-
ditions.
Park the vehicle and shift the shift position to P and block th e wheel
under the vehicle without setting the parking brake. The parkin g brake
may freeze up, preventing it fro m being released. If the vehicle is
parked without setting the parking brake, make sure to block th e
wheels.
Failure to do so may be dangerous because it may cause the vehi cle
to move unexpectedly, possi bly leading to an accident.
Use the correct tire chain size when mounting the tire chains. Chain
size is regulated for each tire size.
Side chain
0.12 in. (3.0 mm)
1.18 in. (30.0 mm)
0.39 in. (10.0 mm)
Cross chain 0.16 in. (4.0 mm)
0.98 in. (25.0 mm)
0.55 in. (14.0 mm)
Regulations regarding the use of tire chains vary depending on loca-
tion and type of road. Always chec k local regulations before installing
chains.
When driving the vehicle
When parking the vehicle
Selecting tire chains
1
2
3
4
5
6
Regulations on the use of tire chains