TOYOTA PRIUS 2001 Service Repair Manual

DI±98
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
8 Check voltage between terminals VC and E2 of ECM connector (See page
DI±81).
NG Check and replace ECM (See page IN±41).
OK
9 Check voltage between terminals PTNK and E2 of ECM connectors (See page
DI±81).
OK Go to step 11.
NG
10 Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page IN±41).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.

BE6653
A12550A14041A14046
ON
F
F E
E VSV is ONVSV is OFF
VSV is ON
VSV is OFF
EVP1
± DIAGNOSTICSENGINE
DI±99
2001 PRIUS (RM778U)
11 Check VSV for EVAP.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Turn the ignition switch ON.
CHECK:
Check VSV function.
(1) Connect between terminal EVP1 of the ECM con-
nector and body ground (VSV ON).
(2) Disconnect between terminal EVP1 of the ECM
connector and body ground (VSV OFF).
OK:
(1) VSV is ON:
Air from port E flows out through port F.
(2) VSV is OFF:
Air does not flow from port E to port F.
OK Go to step 14.
NG
12 Check operation of VSV for EVAP (See page SF±40).
NG Go to step 13.
NG
Replace VSV and clean vacuum hoses between throttle body and VSV for EVAP, and VSV for
EVAP and charcoal canister, and then check charcoal canister.
13 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for EVAP, and VSV for EVAP and ECM (See page
IN±41).
NG Repair or replace harness or connector.
OK

A14042A14043A14047
F
FON
Air
Air E EVSV is ON
VSV is OFF VSV is OFF
VSV is ON
CCV
DI±100
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
Check and replace ECM (See page IN±41).
14 Check VSV for CCV.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect between terminal CCV of the ECM con-
nector and body ground (VSV ON).
(2) Disconnect between terminal CCV of the ECM con-
nector and body ground (VSV OFF).
OK:
VSV is ON:
Air does not flow from port E to port F.
VSV is OFF:
Air from port E flows out through port F.
OK Go to step 17.
NG
15 Check operation of VSV for CCV (See page SF±42).
OK Go to step 16.
NG
Replace VSV and charcoal canister, and then clean vacuum hoses between charcoal canister
and VSV for CCV.
16 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for CCV, and VSV for CCV and ECM (See page IN±41).
NG Repair or replace harness or connector.

A14048BE6653
A14464A14049
FG ON
AirAir
E
EVSV is ON
VSV is OFFVSV is OFF
VSV is ON
TBP
± DIAGNOSTICSENGINE
DI±101
2001 PRIUS (RM778U)
OK
Check and replace ECM (See page IN±41).
17 Check VSV for purge flow switching valve.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect between terminal TBP of the ECM connec-
tor and body ground (ON).
(2) Disconnect between terminal TBP of the ECM con-
nector and body ground (OFF).
OK:
(1) VSV is ON:
Air from pipe E is flowing out through pipe F.
(2) VSV is OFF:
Air from pipe E flows out through pipe G.
OK Check and replace charcoal canister (See page
EC±7).
NG
18 Check operation of VSV for purge flow switching valve (See page SF±45).
OK Go to step 19.
NG
Replace VSV and charcoal canister, and then clean vacuum hoses ((!), (2) and (3) in Fig. 1 in cir-
cuit description).

DI±102
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
19 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for purge flow switching valve, and VSV for purge flow
switching valve and ECM (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±41).

± DIAGNOSTICSENGINE
DI±103
2001 PRIUS (RM778U)
DTC P0450 Evaporative Emission Control System
Pressure Sensor Malfunction
DTC P0451 Evaporative Emission Control System
Pressure Sensor Range/Performance
CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for canister closed valve (CCV) and VSV for pressure switching valve are
used to detect abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTC P0450 or P0451 is recorded by the ECM when the vapor pressure sensor malfunction.
DTC No.DTC Detecting ConditionTrouble Area
P0450
10 seconds or less after engine starting condition (a) or (b)
continues for 7 seconds or more: (2 trip detection logic)
(a) Vapor pressure sensor value < ±4.0 kPa (±30 mmHg, ±1.2
in.Hg)
(b) Vapor pressure sensor value
2.0 kPa (15 mmHg, 0.6
in.Hg)

Open or short in vapor pressure sensor circuit

Vapor pressure sensor
ECM
P0451
Vapor pressure sensor output extremely changes under condi-
tion:
Vehicle speed: 0 km/h (0mph),Engine speed: Idling (2 trip
detection logic)
ECM
WIRING DIAGRAM
Refer to DTC P0440 on page DI±81.
INSPECTION PROCEDURE
HINT:

If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440, first trouble shoot DTC P0441,
P0446 P0450 or P0451. If no malfunction is detected, troubleshoot DTC P0440 next.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for
determining whether the vehicle was running or stopped, the engine was warmed up or not, the air±fuel
ratio was lean or rich, etc. at the time of the malfunction.

When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the
VSV for EVAP, charcoal canister and vapor pressure sensor.
DI7SV±01

DI±104
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
1 Check voltage between terminals VC and E2 of ECM connector (See page
DI±81).
NG Check and replace ECM (See page IN±41).
OK
2 Check voltage between terminals PTNK and E2 of ECM connectors (See page
DI±81).
OK Check and replace ECM (See page IN±41).
NG
3 Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page IN±41).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.

A00022
From
Speed Sensor4±Pulse4±Pulse
Combination
MeterECM ABS ECU
A14030
C10
Combination
Meter
2A7
V±W Instrument Panel J/B
6
2B J27G
V±W5
E10ECM
SPD J28G
B
LJ/C
± DIAGNOSTICSENGINE
DI±105
2001 PRIUS (RM778U)
DTC P0500 Vehicle Speed Sensor Malfunction
CIRCUIT DESCRIPTION
The speed sensor for ABS detects the wheel speed and sends the appropriate signals to the ABS ECU.
The ECU converts these signals into a 4±pulse signal and output it to the combination meter.
After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit in-
side the combination meter, it is then transmitted to the ECM. The determines the vehicle speed based on
the frequency of these pulse signals.
DTC No.DTC Detecting ConditionTrouble Area
P0500
During vehicle is being driven, no vehicle speed sensor signal
to ECM
(2 trip detection logic)

Combination meter

ABS ECU

Open or short in vehicle speed sensor circuit

Vehicle speed sensor

ECM
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI6VG±02

A14009
ON
SPD
(+) (±)
AT7809
4.5 ~ 5.5 V
0
DI±106
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
1 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedmeter in the combination meter is normal.
HINT:
The ABS ECU is operating normally if the speedometer display is normal.
NG Check and replace combination meter (See
page BE±2) and ABS ECU (See page
IN±41).
OK
2 Check voltage between terminal SPD of ECM connector and body ground.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Drive the vehicle.
CHECK:
Measure voltage between terminal SPD of ECM connector and
body ground when the wheel is turned slowly.
OK:
Voltage is generated intermittently.
NG Check and repair harness and connector
between combination meter and ECM.
OK
Check and replace ECM (See page IN±41).

A14031
Throttle Control Motor
with Magnetic ClutchECM
(Shielded)
8
E7M+
7
E7M±
30
E7GE01 L
P 2
1 DI±108
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P1125 Throttle Control Motor Circuit Malfunction
CIRCUIT DESCRIPTION
Throttle motor is operated by the ECM and it opens and closes the throttle valve.
The opening angle of the throttle valve is detected by the throttle position sensor which is mounted on the
throttle body and it provides feedback to the ECM to control the throttle motor in order to the throttle valve
opening angle properly in response to driving condition.
If this DTC is stored, the ECM shuts down the power for the throttle motor, and the throttle valve is fully closed
by the return spring.
DTC No.DTC Detecting ConditionTrouble Area
Conditions (a) and (b) continue for 0.5 seconds:
(a) Throttle control motor output duty
80 %
(b) Throttle control motor current < 0.5 A

Open or short in throttle control motor circuit
P1125Throttle control motor current
16 A
Throttle control motor

ECMCondition (a) continues for 0.6 seconds:
(a) Throttle control motor current
7 A
ECM
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining
whether the vehicle was running or stopped, the engine was warmed up or not, the air±fuel ratio was lean
or rich, etc. at the time of the malfunction.
DI7SW±01