warning light TOYOTA PRIUS PLUG-IN HYBRID 2021 Repair Manual

703
8When trouble arises
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8-1. Essential information
Emergency flashers ........... 704
If your vehicle has to
be stopped in an
emergency ....................... 705
If the vehicle is trapped in
rising water ...................... 706
8-2. Steps to take in an
emergency
If your vehicle needs
to be towed ...................... 707
If you think something is
wrong ............................... 713
If a warning light turns on
or a warning buzzer
sounds ............................. 714
If a warning message is
displayed ......................... 723
If you have a flat tire .......... 731
If the hybrid system will
not start............................ 749
If the electronic key does
not operate properly ........ 751
If the 12-volt battery is
discharged ....................... 755
If your vehicle
overheats ......................... 761
If the vehicle becomes
stuck ................................ 766

7138-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8
When trouble arises
If you think something is wrong
● Fluid leaks under the vehicle
(Water dripping from the air conditioning after use is normal.)
● Flat-looking tires or uneven tire wear
● High coolant temperature warning light flashes or comes on
● Changes in exhaust sound
● Excessive tire squeal when cornering
● Strange noises related to the suspension system
● Pinging or other noises related to the hybrid system
● Engine missing, stumbling or running roughly
● Appreciable loss of power
● Vehicle pulls heavily to one side when braking
● Vehicle pulls heavily to one side when driving on a level road
● Loss of brake effectiveness, spongy feeling, pedal almost touches
the floor
If you notice any of the following symptoms, your vehicle proba-
bly needs adjustment or repair. Contact any authorized Toyota
retailer or Toyota authorized repairer, or any reliable repairer as
soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

7148-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
If a warning light turns on or a warning
buzzer sounds
Calmly perform the following actions if any of the warning lights
comes on or flashes. If a light comes on or flashes, but then
goes off, this does not necessarily indicate a malfunction in the
system. However, if this continues to occur, have the vehicle
inspected by any authorized Toyota retailer or Toyota authorized
repairer, or any reliable repairer.
Warning light and warning buzzer list
Warning lightWarning light/Details/Actions
Brake system warning light and warning buzzer (red
indicator)*1
Indicates that:
• The brake fluid level is low; or
• The brake system is malfunctioning
 Immediately stop the vehicle in a safe place and con-
tact any authorized Toyota retailer or Toyota autho-
rized repairer, or any reliable repairer. Continuing to
drive the vehicle may be dangerous.
Brake system warning light (yellow indicator)
Indicates a malfunction in:
• The regenerative braking system; or
• The electronically controlled brake system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
Charging system warning light
Indicates a malfunction in the vehicle’s charging system
 Immediately stop the vehicle in a safe place and con-
tact any authorized Toyota retailer or Toyota autho-
rized repairer, or any reliable repairer.

7158-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8
When trouble arises
Low engine oil pressure warning light
(warning buzzer)*2
Indicates that the engine oil pressure is too low
 Immediately stop the vehicle in a safe place and con-
tact any authorized Toyota retailer or Toyota autho-
rized repairer, or any reliable repairer.
Malfunction indicator lamp
Indicates a malfunction in:
• The hybrid system;
• The electronic engine control system; or
• The electronic throttle control system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
SRS warning light
Indicates a malfunction in:
• The SRS airbag system; or
• The seat belt pretensioner system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
ABS warning light
Indicates a malfunction in:
• The ABS; or
• The brake assist system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
(Red/yellow)
Electric power steering system warning light (warning
buzzer)
Indicates a malfunction in the EPS (Electric Power Steer-
ing) system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
Warning lightWarning light/Details/Actions

7168-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
(Flashes or illuminates)
PCS warning light
• When a buzzer sounds simultaneously:
Indicates a malfunction has occurred in the PCS (Pre-
Collision System).
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
• When a buzzer does not sound:
The PCS (Pre-Collision System) has become temporar-
ily unavailable, corrective action may be necessary.
 Follow the instructions displayed on the multi-infor-
mation display. ( P. 416, 723)
If the PCS (Pre-Collision System) or VSC (Vehicle Stability
Control) system is disabled, the PCS warning light will illu-
minate.
 P. 428
(Orange)
LTA indicator (warning buzzer)
Indicates a malfunction in the LTA (Lane Tracing Assist)
 Follow the instructions displayed on the multi-infor-
mation display. ( P. 444)
Slip indicator light
Indicates a malfunction in:
• The VSC system;
• The TRC system; or
• The hill-start assist control system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
The light will flash when the ABS, VSC or TRC system is
operating.
High coolant temperature warning light
• When the light flashes:
Indicates that the engine coolant temperature is too high
The light changes from a flashing to a solid light when
the temperature further increases
 Immediately stop the vehicle in a safe place.
( P. 761)
• When the light comes on without flashing:
Indicates a malfunction in the exhaust heat recirculator
system
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
Warning lightWarning light/Details/Actions

7178-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8
When trouble arises
(Flashes) (If equipped)
PKSB OFF indicator
Indicates a malfunction in the Parking Support Brake func-
tion
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer.
The warning light will operate as follows, even when the
system is not malfunctioning:
• The light will come on when the Parking Support Brake
function is turned off ( P. 512)
• The light will come on when the Parking Support Brake
function is operating ( P. 516)
• The light will flash when the system cannot temporarily
be used ( P. 520)
Open door warning light (warning buzzer)*3
Indicates that a door is not fully closed
 Check that all the doors are closed.
Low fuel level warning light
Indicates that remaining fuel is approximately 6.4 L
(1.7 gal., 1.4 Imp.gal.) or less
 Refuel the vehicle.
Driver’s and front passenger’s seat belt reminder light
(warning buzzer)*4
Warns the driver and/or front passenger to fasten their
seat belts
 Fasten the seat belt.
If the front passenger’s seat is occupied, the front
passenger’s seat belt also needs to be fastened to
make the warning light (warning buzzer) turn off.
Rear passengers’ seat belt reminder light (warning
buzzer)*5
Warns the rear passengers to fasten their seat belts
 Fasten the seat belt.
Master warning light
A buzzer sounds and the warning light comes on and
flashes to indicate that the master warning system has
detected a malfunction.
 P. 723
Warning lightWarning light/Details/Actions

7188-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
Tire pressure warning light
When the light comes on:
Low tire inflation pressure such as
• Natural causes ( P. 721)
• Flat tire ( P. 731)
 Adjust the tire inflation pressure to the specified
level.
The light will turn off after a few minutes. In case the
light does not turn off even if the tire inflation pres-
sure is adjusted, have the system checked by any
authorized Toyota retailer or Toyota authorized
repairer, or any reliable repairer.
When the light comes on after blinking for 1 minute:
Malfunction in the tire pressure warning system ( P. 721)
 Have the system checked by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer.
Warning lightWarning light/Details/Actions

7198-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8
When trouble arises
Brake Override System/Drive-Start Control/
Parking Support Brake function (symbol display)*6
Brake Override System
Indicates that the accelerator and brake pedals are being
depressed simultaneously, and the Brake Override Sys-
tem is operating
 Release the accelerator pedal and depress the brake
pedal.
Indicates a malfunction in the Brake Override System
(with warning buzzer)
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
Drive-Start Control
Indicates that the shift position was changed and Drive-
Start Control was operated while depressing the accelera-
tor pedal (with warning buzzer)
 Momentarily release the accelerator pedal.
Indicates a malfunction in the Drive-Start Control system
(with warning buzzer)
 Have the vehicle inspected by any authorized Toyota
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
Parking Support Brake function
Indicates that the Parking Support Brake function (if
equipped) is operating ( P. 516)
 Follow the instruction that is displayed on the multi-
information display.
Warning lightWarning light/Details/Actions

7208-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
*1: Brake system warning buzzer:
When there is a possible problem that could affect braking performance,
the warning light will come on and a warning buzzer will sound.
*2: Low engine oil pressure warning buzzer:
A buzzer also sounds continuously for approximately 30 seconds at maxi-
mum in addition to the low engine oil pressure warning light when the
“READY” indicator is illuminated.
*3: Open door warning buzzer:
The open door warning buzzer sounds to alert one or more of the doors is
not fully closed (with the vehicle having reached a speed of 5 km/h
[3 mph]).
*4: Driver’s and front passenger’s seat belt warning buzzer:
The driver’s and front passenger’s seat belt warning buzzer sounds to alert
the driver and front passenger that his or her seat belt is not fastened. If
the seat belt is unfastened, the buzzer sounds intermittently for a certain
period of time after the vehicle reaches a certain speed.
*5: Rear passengers’ seat belt warning buzzer:
The rear passengers’ seat belt warning buzzer sounds to alert the rear
passenger that his or her seat belt is not fastened. If the seat belt is unfas-
tened, the buzzer sounds intermittently for a certain period of time, after
the seat belt is fastened and unfastened and the vehicle reaches a certain
speed.
*6: This symbol is displayed on the multi-information display.
■ Front passenger detection sensor, seat belt reminder and warning
buzzer
● If luggage is placed on the front passenger seat, the front passenger detec-
tion sensor may cause the warning light to flash and the warning buzzer to
sound even if a passenger is not sitting in the seat.
● If a cushion is placed on the seat, the sensor may not detect a passenger,
and the warning light may not operate properly.
■ Electric power steering system warning light (warning buzzer)
When the 12-volt battery charge becomes insufficient or the voltage tempo-
rarily drops, the electric power steering system warning light may come on
and the warning buzzer may sound.
■ If the malfunction indicator lamp comes on while driving
The malfunction indicator lamp will come on if the fuel tank becomes com-
pletely empty. If the fuel tank is empt y, refuel the vehicle immediately. The
malfunction indicator lamp will go off after several trips.
If the malfunction indicator lamp does not go off, contact any authorized
Toyota retailer or Toyota authorized repai rer, or any reliable repairer as soon
as possible.

7218-2. Steps to take in an emergency
Prius Plug-in Hybrid_OM_OM47D72E_(EE)
8
When trouble arises
■ When the tire pressure warning light comes on
Inspect the appearance of the tire to check that the tire is not punctured.
If the tire is punctured: P. 731
If the tire is not punctured:
Carry out the following procedure after the tire temperature has lowered suffi-
ciently.
● Check the tire inflation pressure and adjust to the appropriate level.
● If the warning light does not go out even after several minutes, check that
the tire inflation pressure is at the specified level and carry out initialization.
( P. 652)
The warning light may come on again if the above operations are conducted
without first allowing the tire temperature to lower sufficiently.
■ The tire pressure warning light may come on due to natural causes
The tire pressure warning light may come on due to natural causes such as
natural air leaks and tire inflation pressure changes caused by temperature.
In this case, adjusting the tire inflation pressure will turn off the warning light
(after a few minutes).
■ Conditions that the tire pressure warning system may not function prop-
erly
 P. 654
■ If the tire pressure warning light frequently comes on after blinking for
1minute
If the tire pressure warning light frequently comes on after blinking for
1 minute when the power switch is turned to ON mode, have it checked by
any authorized Toyota retailer or Toyota authorized repairer, or any reliable
repairer.
■ Warning buzzer
In some cases, the buzzer may not be heard due to being in a noisy location
or audio sound.