engine TOYOTA PRIUS 2001 Service Repair Manual

BE6653A10620A14040A14045
START
ON
OFFVSV for EVAP
1.2 V ON
OFF
E2
PTNK
(±) (+)
VSV for CCV
Measure
Voltage30 sec.
± DIAGNOSTICSENGINE
DI±95
2001 PRIUS (RM778U)
OK
Replace VSV and charcoal canister, and clean vacuum hoses ((1), (2) and (3) in Fig. 1 in circuit
description.
23 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 ECU (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±41).
24 Check fuel tank and charcoal canister.
PREPARATION:
(a) Remove the connector cover from the ECM.
(b) Connect the TOYOTA hand±held tester to the DLC3.
(c) Select the ACTIVE TEST mode on the TOYOTA hand±
held tester.
(d) Start the engine.
(e) The VSV for the CCV is ON by the TOYOTA hand±held
tester.
(f) The VSV for the EVAP is ON by the TOYOTA hand±held
tester and hold the VSV for EVAP until voltage between
terminals PTNK and E2 becomes 1.2 V, then set VSV for
EVAP OFF.
CHECK:
Measure the voltage between terminals PTNK and E2 of the
ECM connectors 30 sec. after switching the VSV for the EVAP
from ON to OFF.
OK:
Voltage: 2.3 V or less
OK Check and replace ECM.
NG

DI±96
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
25 Remove fuel tank and check it.
NG Replace fuel tank.
OK
26 Remove charcoal canister and check it (See page EC±7).
NG Replace charcoal canister.
OK
Check and replace ECM (See page IN±41).
OBD II scan tool (excluding TOYOTA hand±held tester):
1 Check whether hose close to fuel tank have been modified, and check whether
there are signs of any accident near fuel tank or charcoal canister (See page
DI±81).
NG Repair or replace.
OK
2 Check that fuel tank cap is TOYOTA genuine parts.
NG Replace to TOYOTA genuine parts.
OK
3 Check that fuel tank cap is correctly installed.
NG Correctly install fuel tank cap.

± DIAGNOSTICSENGINE
DI±97
2001 PRIUS (RM778U)
OK
4 Check fuel tank cap (See page EC±7).
NG Replace fuel tank cap.
OK
5 Check filler neck for damage.
NG Replace filler pipe.
OK
6 Check VSV connector for EVAP, VSV connector for CCV, VSV connector for
purge flow switching valve and vapor pressure sensor connector for looseness
and disconnection.
NG Repair or connect VSV or sensor connector.
OK
7 Check vacuum hoses ((1), (2) , (3), (4), (5), (6), (7), (8) and (9) in Fig. 1 in circuit
description).
CHECK:
(a) Check that the vacuum hose is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole damage and blockage.
NG Repair or replace.
OK

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.